JLPT N5 Grammar: 〜のです / 〜んです — Explanatory Form

JLPT N5 Grammar: 〜のです / 〜んです

The explanatory form — giving reasons, asking for explanations, and making your Japanese sound natural

JLPTジェイエルピーティー N5エヌゴ文法ぶんぽう〜のです / 〜んです解説かいせつ (説明せつめい)

⏱️ Study time: 6–8 minutes

〜のです (no desu) and its contracted form 〜んです (n desu) add an explanatory tone to your sentence. Use it when you're giving a reason, explaining a situation, or asking for clarification. It's one of the most frequently used patterns in spoken Japanese — and mastering it will make your Japanese sound far more natural.

🚀 JLPT N5 Warm-up Quiz

Q: How do you say “I have a headache, so I want to go home” with an explanatory tone?

Answer: B (頭が痛いんです。家へ帰りたいんです). Adding んです gives an explanatory, natural feel — “I have a headache (you see), so I want to go home.” A is grammatically correct but sounds like a blunt statement without context.

Quick Summary

Grammar Point
〜んです

Meaning
Explanatory / reasoning tone

Pattern
Plain form + んです (casual: んだ)

Example
頭あたまが痛いたいんです。あたまがいたいんです。Atama ga itai n desu.
I have a headache (you see / as an explanation).

📝 Core Patterns

Verb (plain): 行いく + んです → 行いくんです

i‑adjective: 痛いたい + んです → 痛いたいんです

na‑adjective / noun: な + んです → 静しずかなんです / 学生がくせいなんです

⚠️ のです is the formal/written version. んです is the spoken contraction. Both are polite when followed by です/ます.

🧠 Review the plain form? See Verb Groups →

💡 Toggle furigana, hiragana, or romaji for easier reading.

What is 〜のです / 〜んです?

〜んです (contracted from 〜のです) adds an explanatory or reasoning nuance to a sentence. It tells the listener "this is why" or "this is the situation". Without んです, a sentence is a simple statement. With んです, you're providing context, explaining yourself, or asking for an explanation.

Give reasons: 電車でんしゃが遅おくれたんです = The train was delayed (that's why I'm late).
Ask for explanations: どうして来こなかったんですか = Why didn't you come? (I want to know the reason).
Make your Japanese sound engaged and natural in conversation.

すみません、道みちに迷まよったんです。すみません、みちにまよったんです。Sumimasen, michi ni mayotta n desu.
I'm sorry — I got lost (that's why I'm late).

⚡ How to Form 〜んです

Word Type	Plain Form	+ んです	Meaning
Verb	行いく	行いくんです	I'm going (you see)
i‑adjective	痛いたい	痛いたいんです	It hurts (that's why)
na‑adjective	静しずか	静しずかな + んです → 静しずかなんです	It's quiet (you see)
Noun	学生がくせい	学生がくせいな + んです → 学生がくせいなんです	I'm a student (as context)

⚠️ JLPT Trap: na‑adjectives and nouns need な before んです: 静しずかなんです, 学生がくせいなんです. Never 静しずかんです or 学生がくせいんです.

⚡ When to Use 〜んです

Use	Explanation	Example
Giving reasons	Explaining why something happened	電車でんしゃが遅おくれたんです。 The train was delayed (that's why).
Asking for explanations	Seeking a reason or clarification	どうして来こなかったんですか。 Why didn't you come?
Providing context	Softening a statement or making it more engaged	質問しつもんがあるんですが… I have a question (if you don't mind)…

Examples & Mini Dialogue

昨日きのう学校がっこうに来こなかったんですか。きのうがっこうにこなかったんですか。Kinō gakkō ni konakatta n desu ka.
You didn't come to school yesterday? (Asking for an explanation.)

✅ Notice 来なかった (plain past) + んです.

お腹なかがすいたんです。何なにか食たべませんか。おなかがすいたんです。なにかたべませんか。Onaka ga suita n desu. Nanika tabemasen ka.
I'm hungry (that's why I'm asking). Shall we eat something?

🗣️ Mini Dialogue
A: どうして日本語にほんごを勉強べんきょうしているんですか。どうしてにほんごをべんきょうしているんですか。Dōshite Nihongo o benkyō shite iru n desu ka.
B: 日本にほんに留学りゅうがくしたいんです。にほんにりゅうがくしたいんです。Nihon ni ryūgaku shitai n desu.

Common Mistakes (and Fixes)

✕ 静しずかんです (na‑adjective without な).

✓ 静しずかなんです (na‑adjectives need な before んです).

✕ 学生がくせいんです (noun without な).

✓ 学生がくせいなんです (nouns need な before んです).

✕ Using んです with every single sentence — sounds overly dramatic.

✓ Use んです only when giving an explanation, asking for a reason, or adding context.

JLPT N5 Practice Questions

Score: 0 / 3

1. “I have a headache (as an explanation).” Choose the correct form.

2. “It's quiet (you see).” — 静しずか is a na‑adjective. Choose the correct んです form.

3. んです is used for:

🎯 JLPT N5 tip: んです appears in both grammar and listening sections. When you hear んですか, the speaker is asking for an explanation. When you hear んです in a reply, the speaker is giving a reason. Recognise the な before んです with nouns and na‑adjectives — it's a common trap.

Test yourself with a free mock exam →

About the Instructor

Taught by Anup Sensei at Gogaku Language & Training Center in Pokhara. With real Japan experience and a focus on exam essentials, he helps students pass the JLPT with confidence.

⚡ Vocabulary Used in This Lesson

Japanese	Reading	Type	English Meaning
頭あたま	あたま	Noun	head
痛いたい	いたい	i‑adjective	painful, sore
電車でんしゃ	でんしゃ	Noun	train
遅おくれる	おくれる	Ichidan verb	to be delayed
道みち	みち	Noun	road, way
迷まよう	まよう	Godan verb	to get lost
留学りゅうがくする	りゅうがくする	Irregular verb	to study abroad

Related Grammar

Frequently Asked Questions

What's the difference between のです and んです?

んです is the contracted, spoken form of のです. Both are polite when followed by です/ます. In formal writing, use のです. In conversation, んです is far more common and natural.

Why do na‑adjectives and nouns need な before んです?

な is the attributive form of the copula だ that connects na‑adjectives and nouns to の/ん. It's the same な that appears in な-adjective + noun (静かな部屋).

Can I use んです with ます form?

No. The word before んです must be in the plain form: 行くんです ✓, 行きますんです ✕.

Continue Learning

Next: から (kara) — giving reasons with the reason particle.

Learn から →

→ Explore the JLPT N5 Grammar Hub

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