Two Negative Systems — When to Use Each
Japanese has two main negative systems: the polite negative (〜ません) and the plain negative (〜ない). Mixing them up — or forming them incorrectly — is one of the most common beginner mistakes.
The Two Negative Systems
| Style | Non-past negative | Past negative | Use |
|---|---|---|---|
| Polite | 〜ません | 〜ませんでした | Formal situations, speaking to superiors |
| Plain | 〜ない | 〜なかった | Casual, inner speech, embedded clauses |
Forming Plain Negative (〜ない) — The Rules
| Verb group | Change | Example |
|---|---|---|
| Group 1 (u-verbs) | Final う-sound → あ-sound + ない | かく→かかない、のむ→のまない、いく→いかない |
| Group 2 (ru-verbs) | Drop る → ない | たべる→たべない、みる→みない |
| する | Irregular: しない | |
| くる | Irregular: こない |
Special Case: う-ending verbs → わない (NOT あない)
Verbs ending in う change to わない, not あない:
- かう (to buy) → かわない ✓ (NOT かあない ✗)
- いう (to say) → いわない ✓
- あう (to meet) → あわない ✓
Common Mistakes
| Wrong | Correct | Problem |
|---|---|---|
| たべません (in casual speech mid-sentence) | たべない | Polite form in casual embedded clause |
| かあない | かわない | Wrong vowel change for う-ending verbs |
| しません (irregular) | しない | Must use irregular form for する |
| 〜ないでした | 〜ませんでした / 〜なかった | ない is an adjective — its past is なかった, not ないでした |
Plain Negative in Embedded Clauses
Even in polite sentences, the embedded clause (inside the sentence) uses the plain form:
- 「さかなをたべないひとがいます。」— There are people who don’t eat fish. (plain ない inside)
- 「いかないつもりです。」— I intend not to go. (plain ない inside)
Quick Drill
- Plain negative of のむ?
- Plain negative of くる?
- Plain past negative of たべる?
- Correct: 「かあない」
Answers: 1. のまない / 2. こない / 3. たべなかった / 4. かわない
Yuka Mixes Up Negative Forms
Mistakes feel embarrassing in the moment but they are the fastest way to learn. Watch how Yuka makes a natural error — and how Rei explains the rule clearly enough to prevent it from happening again.
YukaRei, I wanted to say ‘I can’t go’ and said いきないです. Wrong?
ReiYes — いきないです is not standard. For the plain negative of いく, it’s いかない. Polite negative: いきません. So ‘I can’t go’ (lack of ability) is いけません — from いける, the potential form.
YukaWait — いかない vs いけない? What’s the difference?
Reiいかない = not going (won’t / don’t). いけない = can’t go / must not go. The potential form changes the meaning completely. ‘I won’t go’ vs ‘I’m unable to go’ — very different situations!
YukaAnd how do I make any verb negative politely? Is it always 〜ません?
ReiYes for present/future: verb stem + ません. たべる → たべません. For past: ませんでした. For て-form negative (asking not to do): 〜ないでください — please don’t do ~. Like ここでたばこをすわないでください — please don’t smoke here.
5 Correct Sentences — Read These Aloud
Each sentence demonstrates the correct usage from this article. Say them aloud to lock in the right pattern.
- きょうはがっこうにいきません。
I’m not going to school today. (polite negative) - このえいがはみていません。
I haven’t watched this movie. (て-form + いません) - ここでしゃしんをとらないでください。
Please don’t take photos here. (〜ないでください) - にほんごがうまくはなせません。
I can’t speak Japanese well. (potential negative) - さとうはいれないでください。アレルギーがあります。
Please don’t add sugar. I have an allergy.
Your Turn! Correct the Mistake in the Comments
Here is a sentence with the error from this article. Can you fix it? Write the corrected version — and your own correct sentence — in the comments below.
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