関係代名詞って難しそうに聞こえるけど、実は2つの文を1つにくっつける便利な道具なんだ！長い英語を読むときや、自分で書くときにも絶対に必要な文法だよ。
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Updated May 4, 2026
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関係代名詞（Who, Which, That）の使い方を解説
1 / 5
関係代名詞の基礎
君の周りにいる人やものを詳しく説明したいとき、どうする？関係代名詞を使えば、2つの文を1つにつなげて、もっと自然でカッコいい英語が作れるようになるんだ。
先行詞っていうのは、関係代名詞が説明する直前の名詞のこと。この先行詞が「人」なのか「もの・動物」なのかで、使う関係代名詞が決まるよ。
関係代名詞は文と文をくっつける接着剤みたいな役割をしてる。まずはwho, which, thatの3つを覚えよう！
重要ポイント: 関係代名詞の後ろには、もともとあった主語（He, She, Itなど）が消えた不完全な文が続くよ。これがテストでよく狙われる部分だから要注意！
詳しい使い方
先行詞によって使い分けるのがコツ！人にはwho、もの・動物にはwhich、そして万能なthatは両方に使える。
先行詞が「人」のときはwhoを使う。例えば「I know the girl + She has long hair」を1つにすると、「I know the girl who has long hair」になる。
先行詞が「もの・動物」のときはwhichを使う。「This is the key + It opens the door」なら、「This is the key which opens the door」だね。
thatは人にもものにも使える便利な関係代名詞。会話ではthatがよく使われるけど、学校のテストでは「whoかwhichを使いなさい」って指定されることもあるから注意して！
覚え方のコツ: 先行詞を見て「人？もの？」って判断する癖をつけよう。慣れれば一瞬で分かるようになるよ！
例文で練習
実際に2つの文を1つにする練習をしてみよう！手順は簡単で、共通部分を見つけて、先行詞を決めて、関係代名詞を選ぶだけ。
「The man is a famous actor + He lives near my house」の場合、共通部分は「The man = He」。先行詞は「The man（人）」だから、whoを使って「The man who lives near my house is a famous actor」になる。
「I have a dog + It runs very fast」なら、共通部分は「a dog = It」。先行詞は「a dog（動物）」だから、whichを使って「I have a dog which runs very fast」だね。
関係代名詞の節は、説明したい名詞のすぐ後ろに割り込む形になるのがポイント。文の最後に置いたりしないよ！
練習のコツ: 最初はゆっくりでいいから、手順通りにやってみよう。慣れれば自然にできるようになるから大丈夫！
テストのポイント・注意点
一番やりがちなミスは、もとの文の主語を消し忘れること！「I have a friend who he lives in Osaka」じゃなくて、「I have a friend who lives in Osaka」が正解だよ。
先行詞が単数か複数かで、関係代名詞の後の動詞の形も変わる。「The boy who is reading」（単数）と「The boys who are reading」（複数）みたいにね。
whatとの違いも要注意！whatは「〜なこと・もの」という意味で、前に先行詞がない。「This is what I bought（これが私が買ったものです）」みたいに使うよ。
関係代名詞は先行詞のすぐ後ろに置くこと。離れた場所に置いちゃダメだからね！
テスト必勝法: ミスしやすいポイントを覚えておけば、関係代名詞は怖くない！練習すれば必ずできるようになるよ。
まとめ
試験前にこれだけは絶対チェック！先行詞が人ならwho/that、もの・動物ならwhich/thatを使う。
関係代名詞は先行詞のすぐ後ろに置いて、もとの文の主語（he, itなど）は必ず消す。これだけ覚えておけば基本はOK！
関係代名詞の節は、先行詞を説明するかたまりとして考えよう。「I saw a girl [who was carrying a red bag]」なら、「私は[赤いカバンを持っていた]女の子を見ました」って感じ。
君も練習すれば、長くてカッコいい英語が書けるようになる！最初は難しく感じるかもしれないけど、コツを掴めば絶対にマスターできるよ。
最後のアドバイス: 関係代名詞は英語の基本中の基本！ここをしっかり理解しておけば、今後の英語学習がグッと楽になるからね。
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The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
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Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
関係代名詞（Who, Which, That）の使い方を解説
関係代名詞って難しそうに聞こえるけど、実は2つの文を1つにくっつける便利な道具なんだ！長い英語を読むときや、自分で書くときにも絶対に必要な文法だよ。
関係代名詞の基礎
君の周りにいる人やものを詳しく説明したいとき、どうする？関係代名詞を使えば、2つの文を1つにつなげて、もっと自然でカッコいい英語が作れるようになるんだ。
先行詞っていうのは、関係代名詞が説明する直前の名詞のこと。この先行詞が「人」なのか「もの・動物」なのかで、使う関係代名詞が決まるよ。
関係代名詞は文と文をくっつける接着剤みたいな役割をしてる。まずはwho, which, thatの3つを覚えよう！
重要ポイント: 関係代名詞の後ろには、もともとあった主語（He, She, Itなど）が消えた不完全な文が続くよ。これがテストでよく狙われる部分だから要注意！
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詳しい使い方
先行詞によって使い分けるのがコツ！人にはwho、もの・動物にはwhich、そして万能なthatは両方に使える。
先行詞が「人」のときはwhoを使う。例えば「I know the girl + She has long hair」を1つにすると、「I know the girl who has long hair」になる。
先行詞が「もの・動物」のときはwhichを使う。「This is the key + It opens the door」なら、「This is the key which opens the door」だね。
thatは人にもものにも使える便利な関係代名詞。会話ではthatがよく使われるけど、学校のテストでは「whoかwhichを使いなさい」って指定されることもあるから注意して！
覚え方のコツ: 先行詞を見て「人？もの？」って判断する癖をつけよう。慣れれば一瞬で分かるようになるよ！
Sign up to see the contentIt's free!
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例文で練習
実際に2つの文を1つにする練習をしてみよう！手順は簡単で、共通部分を見つけて、先行詞を決めて、関係代名詞を選ぶだけ。
「The man is a famous actor + He lives near my house」の場合、共通部分は「The man = He」。先行詞は「The man（人）」だから、whoを使って「The man who lives near my house is a famous actor」になる。
「I have a dog + It runs very fast」なら、共通部分は「a dog = It」。先行詞は「a dog（動物）」だから、whichを使って「I have a dog which runs very fast」だね。
関係代名詞の節は、説明したい名詞のすぐ後ろに割り込む形になるのがポイント。文の最後に置いたりしないよ！
練習のコツ: 最初はゆっくりでいいから、手順通りにやってみよう。慣れれば自然にできるようになるから大丈夫！
Sign up to see the contentIt's free!
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テストのポイント・注意点
一番やりがちなミスは、もとの文の主語を消し忘れること！「I have a friend who he lives in Osaka」じゃなくて、「I have a friend who lives in Osaka」が正解だよ。
先行詞が単数か複数かで、関係代名詞の後の動詞の形も変わる。「The boy who is reading」（単数）と「The boys who are reading」（複数）みたいにね。
whatとの違いも要注意！whatは「〜なこと・もの」という意味で、前に先行詞がない。「This is what I bought（これが私が買ったものです）」みたいに使うよ。
関係代名詞は先行詞のすぐ後ろに置くこと。離れた場所に置いちゃダメだからね！
テスト必勝法: ミスしやすいポイントを覚えておけば、関係代名詞は怖くない！練習すれば必ずできるようになるよ。
Sign up to see the contentIt's free!
Access to all documents
Improve your grades
Join milions of students
まとめ
試験前にこれだけは絶対チェック！先行詞が人ならwho/that、もの・動物ならwhich/thatを使う。
関係代名詞は先行詞のすぐ後ろに置いて、もとの文の主語（he, itなど）は必ず消す。これだけ覚えておけば基本はOK！
関係代名詞の節は、先行詞を説明するかたまりとして考えよう。「I saw a girl [who was carrying a red bag]」なら、「私は[赤いカバンを持っていた]女の子を見ました」って感じ。
君も練習すれば、長くてカッコいい英語が書けるようになる！最初は難しく感じるかもしれないけど、コツを掴めば絶対にマスターできるよ。
最後のアドバイス: 関係代名詞は英語の基本中の基本！ここをしっかり理解しておけば、今後の英語学習がグッと楽になるからね。
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
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4.6/5
App Store
4.7/5
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because it’s too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didn’t even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as I’m sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH 😍😁😲🤑💗✨🎀😮
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user