Grammar Rule in 30 Seconds
Non-defining clauses add extra, non-essential information about a noun using commas and relative pronouns like 'who' or 'which'.
- Always use commas to separate the extra info from the main sentence: 'My brother, who lives in Paris, is a chef.'
- Never use the word 'that' in these clauses; stick to 'who', 'which', 'whose', or 'where'.
- The sentence must still make perfect sense if you remove the entire clause between the commas.
Overview
My sister, who lives in Tokyo, is coming to visit （東京に住んでいる姉が遊びに来るんだ）と言う時は non-defining clause を使う。だって、姉妹は一人しかいないんだから、友達は「どの」姉妹の話かもう分かってるでしょ？彼女が東京に住んでいるというのは、グループチャットに投下するただのクールなおまけ情報に過ぎない。でも、もし5人の姉妹がいて、そのうちの誰かを特定する必要があるなら、それは全く別のルールになる。これらの節（clause）は、「ところで（By the way）」というエネルギーの王様なんだ。これを使えば、複雑な詳細をストーリーやインスタのキャプション、仕事のメールに織り交ぜることができる。新しい文を書き始める必要もない。覚えておいて：この節は、ブランチでいつも喋りすぎる友達みたいなもの。面白いけど、話の筋にとって厳密に必要ってわけじゃないんだ。How This Grammar Works
Paris, which is the capital of France, is beautiful. （フランスの首都であるパリは美しい）。パリが何かなんてみんな知ってるよね。「フランスの首都である」という部分を追加しても、街を特定する役には立たない。ただ彩りを添えているだけだ。これを成立させるために、who、which、where、whose といった関係代名詞（relative pronouns）を使う。でも、ここで黄金のルールがある：non-defining clause では絶対に that を使っちゃダメだ。それはスープをフォークで食べようとするようなもの――うまくいかないし、滑稽に見えちゃうよ。それから、代名詞を省略することもできない。他の文なら 'The book I read' と言えるかもしれないけど、ここでは The book, which I finished last night, was boring. と言わなきゃいけない。そのおまけ情報への架け橋として、代名詞が必要なんだ。クラブのVIP席みたいなものかな。明確な境界線（カンマ）と、that を含まないゲストリスト（代名詞）があるんだ。
Formation Pattern
My mom、Netflix、London）。
who、物には which、場所には where、所有には whose を使う。
My laptop (1), (2) which (3) I bought only last month (4), (5) is already acting like it's 100 years old (6). （先月買ったばかりのノートPCが、もう100年前の代物みたいな動きをしてる）。この「カンマ・サンドイッチ」のテクニックさえ掴めば、流れはシンプルだよ！
When To Use It
My former boss, who recently started her own company, is hiring. （最近自分の会社を立ち上げた元上司が、人を募集している）。あるいは Instagramのキャプション：This sunset, which I caught just before the rain started, was magical. （雨が降り出す直前に撮れたこの夕日は魔法みたいだった）。旅行のVlogで名所を紹介する時にもピッタリだ：The Colosseum, where gladiators used to fight, is even bigger in person. （かつて剣闘士たちが戦ったコロッセオは、実物はもっと大きい）。Netflixの字幕やニュースレポートでも、登場人物や出来事の背景を説明するために頻繁に出てくる。基本的に、「ちなみに」とか「ご存知の通り」と言いたい時はいつでも、non-defining relative clause が親友になってくれる。これを使えば文章の流れが良くなるし、短くて切れ切れの文を50個も並べるのを防げる。ロボットみたいに聞こえるか、上手な物語の語り方を知っているネイティブスピーカーみたいに聞こえるか、その違いはここにあるんだ。それに、Zoomでの就職面接で以前の役割を説明する時に、文法スキルを見せつける良い方法でもあるよ。
Common Mistakes
that を使うこと。覚えておいて：that は必須情報（essential info）専用だ。My dog, that is a pug, is sleeping. とは言えない。My dog, which is a pug, is sleeping. と言わなきゃいけない（実は、名前のあるペットには、愛情を込めて who を使うことがよくあるけどね！）。もう一つの罠は、代名詞を消そうとすること。他のタイプの節では who や which を省略できることがよくあるけど、ここではキープしなきゃダメだ。My car, I bought last year, is fast は完全にアウト。その which が必要なんだ。最後に、2つ目のカンマを忘れないこと！多くの人がカンマで節を始めるけど、閉じるのを忘れて、おまけ情報を宙ぶらりんにしてしまう。括弧の片方だけ閉じるようなもので、なんかしっくりこない。片方の靴だけ履いて家を出るようなものだね。みんな気づくし、気まずいことになるよ。Contrast With Similar Patterns
The man who lives next door is a spy. （隣に住んでいる男はスパイだ）。もし who lives next door を取り除いたら、ただ The man is a spy. （その男はスパイだ）と言っていることになる。どの男？誰も分からないよね！ここではカンマは使わない。でも、僕らの non-defining バージョンではこうなる：Mr. Smith, who lives next door, is a spy. （隣に住んでいるスミスさんはスパイだ）。スミスさんだってもう分かってる。「隣に住んでいる」という部分はただの面白い事実だ。「削除テスト」を使ってみよう――もし節を削除しても文の意味が通じて、同じ人/物を特定できるなら、それは non-defining だ。あと、that のルールも思い出して。Defining clauses は that が大好きだけど（The phone that I want is expensive）、non-defining clauses はそれが大嫌いだ。Mac vs PC よりも根深い対立なんだよ。Quick FAQ
whoever や whichever は使える？
実はそうでもない。それらは別の構文用だ。基本に忠実に、これら特定の「おまけ情報」節には who、which、where、whose を使おう。
おまけ情報が文の最後に来る場合は？
簡単！代名詞の前にカンマを一つ置いて、最後にピリオドを打つだけ。こんな感じ：I'm going to visit London, which is my favorite city.
動物に who を使ってもいい？
その動物に名前があったり、個人的なつながりを感じるなら、使っちゃえ！もし単に「一匹のクモ（a spider）」とか「その鳥（the bird）」とかなら、which の方が無難だね。
これを使うと堅苦しく聞こえる？
全然！ただ「教養がある（articulate）」ように聞こえるだけだ。カジュアルなテキストでさえ、ちょっとした which 節を使うことで言いたいことがより明確になるよ。
なんで that は使えないの？
正直なところ？それは英語の「私がそう言ったから（because I said so）」っていうルールの一つなんだ。昔々、文法学者たちが that は必須情報専用だと決めて、それ以来僕らはそれに縛られているってわけ。ただ which を受け入れよう！
Memory Trick
カンマを 「The Handles（取っ手）」 だと考えよう。バスケットに2つの取っ手があって持ち上げて移動できるのと同じように、non-defining clause には2つのカンマがあって、おまけ情報を拾い上げて文から「持ち上げる」ことができるんだ。もしバスケットを「持ち上げた」後でも文が完璧に自立しているなら、そのカンマはそこにあるべきだったってこと！
Relative Pronoun Selection
| Target | Pronoun | Example Clause |
|---|---|---|
|
People
|
who
|
, who lives next door,
|
|
Things/Animals
|
which
|
, which cost $50,
|
|
Possession
|
whose
|
, whose car was stolen,
|
|
Places
|
where
|
, where we met,
|
|
Time
|
when
|
, when the sun sets,
|
|
Whole Sentences
|
which
|
, which is why I'm late.
|
Meanings
A non-defining relative clause provides additional information about a person, thing, or place that is already clearly identified. It is not essential for the sentence to be understood.
Adding info about people
Using 'who' to provide biographical or situational details about a specific person.
“Mr. Smith, who is 70 years old, still goes jogging every morning.”
“My sister, who you met yesterday, is moving to Canada.”
Adding info about things
Using 'which' to describe an object or concept that has already been named.
“The Taj Mahal, which was built in the 17th century, is a UNESCO World Heritage site.”
“My new phone, which cost a fortune, is already broken.”
Possession with 'whose'
Adding extra info about who something belongs to.
“The neighbor, whose dog barks all night, is actually very nice.”
“The company, whose profits have doubled, is hiring new staff.”
Adding info about places
Using 'where' to give extra context about a location.
“Paris, where I spent my honeymoon, is beautiful in the spring.”
“The local park, where we used to play football, has been closed.”
Commenting on a whole sentence
Using 'which' after a comma to comment on the entire preceding clause.
“He arrived late, which was very rude.”
“She passed the exam, which surprised everyone.”
Reference Table
| 関係代名詞 | 指すもの | 非制限用法の例文 | 制限用法の例文 |
|---|---|---|---|
|
who
|
人
|
My sister, who lives in Canada, is visiting soon.
|
The student who aced the exam got a scholarship.
|
|
whom
|
人 (目的語、フォーマル)
|
The CEO, whom I met yesterday, was very approachable.
|
The person whom you spoke to earlier has left.
|
|
whose
|
所有 (人・物)
|
My dog, whose name is Loki, loves chasing squirrels.
|
I know a guy whose car is electric.
|
|
which
|
物・アイデア
|
The new café, which has amazing pastries, is always busy.
|
The book which I borrowed from you is fantastic.
|
|
where
|
場所
|
London, where I grew up, is a vibrant city.
|
The park where we first met is beautiful.
|
|
when
|
時
|
Next Tuesday, when the new movie comes out, I'm going.
|
I remember the day when we graduated.
|
フォーマル度スペクトル
My brother, who resides in London, is a medical practitioner. (Family description)
My brother, who lives in London, is a doctor. (Family description)
My brother, who's living in London now, is a doctor. (Family description)
My bro, who's up in London, is a doc. (Family description)
非制限用法：「おまけ情報」マップ
主な特徴
- コンマ 必ずコンマを使う！
- 省略可能 なくても文は意味が通じる
- That はナシ ここでは 'that' を使わない
関係代名詞
- Who 人に対して
- Which 物事・アイデアに対して
- Whose 所有に対して
- Where 場所に対して
- When 時間に対して
目的
- 詳細を加える より多くの文脈を与える
- 余談 意見やコメントを提示する
- 会話を豊かにする より自然に聞こえる
制限用法 vs. 非制限用法：違いを見つけよう！
関係節の選び方：クイックガイド
その情報は名詞を特定するために必須ですか？
その節は人を指しますか？
その節は物事やアイデアを指しますか？
その節は所有を示しますか？
その節は場所を指しますか？
その節は時間を指しますか？
非制限用法のための代名詞
人に対して
- • who
- • whom (formal)
- • whose
物事・アイデアに対して
- • which
- • whose
場所に対して
- • where
時間に対して
- • when
レベル別の例文
My dad, who is a teacher, is nice.
London, which is big, is in England.
My car, which is red, is fast.
Sarah, who is my friend, is here.
My house, which has three bedrooms, is old.
The teacher, who is very kind, helped me.
Paris, where the Eiffel Tower is, is beautiful.
My brother, whose name is Tom, is a doctor.
The new shopping mall, which opened last week, is huge.
My boss, who travels a lot, is in New York now.
The movie, which we saw yesterday, was quite boring.
Italy, where my parents were born, is a sunny country.
The company, which was founded in 1920, is going bankrupt.
He forgot my birthday, which made me very angry.
The scientist, whose research is famous, won a prize.
The hotel, where we stayed for two weeks, was excellent.
The proposal, which the board rejected yesterday, was very detailed.
The city, the history of which is fascinating, attracts many tourists.
The witness, who had been silent until then, finally spoke.
The project, which I have been working on for months, is finally finished.
The Prime Minister, whose popularity has waned recently, faces a challenge.
The cathedral, the construction of which took 200 years, is a masterpiece.
He was unable to attend, which, given the circumstances, was understandable.
The theory, which has been widely criticized, remains influential.
間違えやすい
Learners don't know when to use commas and when not to.
Learners want to use 'that' in all relative clauses.
よくある間違い
My brother that is tall is here.
My brother, who is tall, is here.
London which is big is in England.
London, which is big, is in England.
My car, that I bought last year, is broken.
My car, which I bought last year, is broken.
The city where I was born in is beautiful.
The city, where I was born, is beautiful.
文型パターン
[Proper Name], who ___, is ___.
[Specific Object], which ___, was ___.
[Clause], which ___.
Real World Usage
The President, who is 78, arrived today.
My cat, which is literally a demon, just broke my vase.
My last project, which I led for six months, was a success.
The hotel, where we stayed last summer, has closed down.
I saw Sarah, who says hi btw.
This theory, which was developed in 1920, is still used.
コンマが「道しるべ」
If you remove the clause, the main sentence still makes sense.
ここでは "that" はダメ！
that は決して使いません。代わりに who, which, whose, where, when を使いましょう。 "It's a common error to use 'that' here."声に出して「リズム」を確認
Reading aloud helps with comma placement.
会話がもっと「豊か」に！
Mastering them will make your English sound much more natural.
Smart Tips
Always use commas. Since the name already identifies them, any extra info is by definition 'non-defining'.
Use ', which' at the end of your sentence to add a comment.
Make sure the place is a setting. If you are describing the place as an object, use 'which'.
Combine them! Use a non-defining clause to turn two boring sentences into one interesting one.
発音
The Comma Pause
In speech, there is a slight pause and a drop in pitch at each comma.
Parenthetical Dip
The car, ↘ which was red, ↗ is mine.
The lower pitch indicates the information is secondary.
暗記しよう
記憶術
Commas are like handles on a suitcase: they hold the extra stuff you're carrying.
視覚的連想
Imagine a 'comma sandwich'. The two commas are the bread, and the extra information is the delicious filling. Without the bread, the filling falls out and makes a mess!
Rhyme
If the info is just a plus, use a comma and don't make a fuss.
Story
A detective is describing a suspect. 'The man is tall.' (Boring). 'The man, who was wearing a red hat, is tall.' The red hat is the extra clue that helps the story but isn't the main point.
Word Web
チャレンジ
Look at three objects in your room. Write one sentence for each using a non-defining clause (e.g., 'My laptop, which I bought last year, is on the desk.').
文化メモ
British speakers are often very strict about using 'which' for non-defining clauses and 'that' for defining ones.
News outlets like the BBC or NYT use these clauses to provide titles and ages efficiently.
Non-defining clauses are used to cite sources or provide definitions without stopping the flow.
Relative clauses in English evolved from demonstrative pronouns in Old English.
会話のきっかけ
Tell me about your best friend, who I haven't met yet.
What is your favorite city, which you've visited recently?
Tell me about your first car, which you probably don't have anymore.
日記のテーマ
よくある間違い
Test Yourself
My best friend ___ is a brilliant artist, just had her first exhibition.
Find and fix the mistake:
The new cafe that has a rooftop terrace is very popular.
Arrange the words in the correct order:
All words placed
Click words above to build the sentence
Score: /3
練習問題
8 exercisesWhich sentence is punctuated correctly?
Paris, ___ is the capital of France, is beautiful.
Find and fix the mistake:
My car, that I bought last week, is already broken.
Mr. Jones is our neighbor. He is 80 years old.
You can use 'that' in a non-defining relative clause.
The book, which I finished yesterday, was great.
Match the following:
my / which / is / old / car / , / red / , / is
Score: /8
Practice Bank
12 exercisesMy phone ___ I bought last year, is already acting up.
My boss, that is usually very strict, was surprisingly lenient today.
Choose the correct sentence:
Translate into English: 'Mi hermana, que vive en Madrid, viene a visitarme.'
Arrange these words into a sentence:
Match the subjects with the correct non-defining clause:
The concert, ___ tickets sold out in minutes, was spectacular.
The movie, I watched last night, was incredibly boring.
Choose the correct sentence:
Translate into English: 'El lunes, cuando tengo mi examen final, estaré muy estresado.'
Arrange these words into a sentence:
Match the main clause beginnings with appropriate non-defining clause endings:
Score: /12
よくある質問 (8)
No, never. In English, 'that' is strictly for defining clauses. If you have commas, you must use 'who' or 'which'.
It creates a 'run-on' feeling and can confuse the reader about where the main verb of the sentence is.
Yes, in very formal writing, 'whom' is used if the person is the object of the clause: 'My boss, whom I respect, is leaving.'
Yes! This is called a sentential relative clause. Example: 'He was late, which was annoying.'
You only need the first comma. Example: 'I live in London, which is a big city.'
Try the 'Deletion Test'. If you remove it and the sentence still identifies the noun clearly, it's extra (non-defining).
Yes, for places. 'My school, where I studied for 5 years, is closing.'
It is very common in both, but you will see much longer and more complex ones in formal writing.
Scaffolded Practice
1
2
3
4
Mastery Progress
Needs Practice
Improving
Strong
Mastered
In Other Languages
Oraciones de relativo explicativas
Spanish uses 'que' for both; English requires 'which/who' and forbids 'that'.
Relativsätze
German always uses commas; English only uses them for non-defining clauses.
Propositions subordonnées relatives
French 'que' is used for objects, while English uses 'which' or 'who(m)'.
連体修飾節 (Rentai shuushikusetsu)
Japanese has no relative pronouns and the clause precedes the noun.
الصلة (Al-Sila)
Arabic relative pronouns change based on gender and number, and the definite/indefinite distinction is crucial.
的 (de) structure
Chinese puts all descriptions before the noun using 'de'.
Learning Path
Prerequisites
Learn These First
Continue With
関連動画
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07:59 This Is Where We’re Gonna Bury The ISS
05:21 Why are there two tides a day? - Elise Cutts
Relative Clauses (Defining & Non-Defining) | EasyTeaching
EasyTeaching
Defining and Non-Defining Relative Clauses - English Grammar Lesson
Oxford English Now
Reduced Relative Clauses - Defining and Non- Defining Relative Clauses - Advanced Grammar Lesson
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