の joins two nouns. The first noun explains the second noun, so the main noun always comes last. This order is the same as English 'my book' but the opposite of 'a book of mine', and the opposite of Vietnamese. の is often translated as ''s' or 'of', but its meaning is wider: it only says that the first noun tells us something about the second.
§1Structure
Noun A + の + Noun B. A gives more information about B, and B is the main noun. の can show the owner (わたしの本), the group someone belongs to (日本語学校の学生), the kind or content (日本語の本), the place something comes from (日本の車), the time (きのうの晩ごはん), or that A and B are the same person (友だちの田中さん). You can use の more than once: わたしの母の誕生日.
§2Examples
これはわたしのかさです。
これはわたしのかさです。
This is my umbrella.
リンさんは日本語学校の学生です。
リンさんはにほんごがっこうのがくせいです。
Linh is a student at a Japanese language school.
それは日本語の本じゃありません。英語の本です。
それはにほんごのほんじゃありません。えいごのほんです。
That is not a Japanese book. It is an English book.
これはだれのかばんですか。
これはだれのかばんですか。
Whose bag is this?
きのうの晩ごはんはカレーでした。
きのうのばんごはんはカレーでした。
Yesterday's dinner was curry.
こちらは友だちの田中さんです。
こちらはともだちのたなかさんです。
This is my friend, Mr. Tanaka.
わたしの母の誕生日は3月です。
わたしのははのたんじょうびはさんがつです。
My mother's birthday is in March.
これは妹の写真だ。
これはいもうとのしゃしんだ。
This is a photo of my younger sister. (plain style)
§3Common mistakes
- Putting the two nouns in the wrong order. ✗ 先生の日本語 (for 'a teacher of Japanese') → ✓ 日本語の先生. The main noun comes last. 先生の日本語 is possible Japanese, but it means 'the teacher's Japanese'. Vietnamese speakers should be careful, because the Vietnamese order (giáo viên tiếng Nhật) is the opposite.
- Leaving out の between two nouns. ✗ わたし本 / ✗ 日本語本 → ✓ わたしの本 / ✓ 日本語の本. Two separate nouns normally need の between them. Some fixed words, such as 日本語学校, have no の; learn these as one word.
- Adding の after an adjective. ✗ 大きいのかばん / ✗ きれいの花 → ✓ 大きいかばん / ✓ きれいな花. の joins a noun to a noun. An い-adjective goes directly before the noun, and a な-adjective takes な.
§4How it's different from similar grammar
- 〜の as 'one' / 'mine' (わたしの, 赤いの)
- In noun + の + noun, the second noun is said: これはわたしのかさです (This is my umbrella). When the second noun is already clear, you can leave it out and stop at の: このかさはわたしのです (This umbrella is mine). Here の stands for かさ.
- な-adjective + な + noun
- A noun takes の before another noun, but a な-adjective takes な: 病気の人 (a sick person; 病気 is a noun) and 元気な人 (a healthy, lively person; 元気 is a な-adjective). When you learn a new word, check whether it is a noun or a な-adjective.
§5How this shows up on the JLPT
In N5 grammar Part 1, の is a very common answer when the blank is between two nouns (わたし＿＿本, 日本＿＿車). The wrong choices are often な, に or を. In Part 2 (sentence building with ★), long chains such as わたしの友だちの名前 appear: put the pieces in order from the owner to the main noun, with the main noun last. In reading, だれの asks for the owner and 何の asks for the kind (何の本ですか — 料理の本です).
§6Quick check (3 questions)
1. Choose the particle that fits the blank: これはわたし＿＿かさです。
これはわたし＿＿かさです。
2. Which sentence correctly says 'Mr. Tanaka is a teacher of Japanese'?
3. In あの人は医者の田中さんです, what does 医者の田中さん mean?
あのひとはいしゃのたなかさんです