What is Nai-form?
ない-form (nai-form) is the plain/casual negative present/future. It means "don't/won't do something" in casual speech.
食べない (tabenai) - don't eat / won't eat
行かない (ikanai) - don't go / won't go
しない (shinai) - don't do / won't do
When to Use Nai-form
1. Casual Negative Statements
With friends, family, in casual situations:
今日は行かない
"I won't go today"
肉食べない
"I don't eat meat"
分からない
"I don't understand"
2. Informal Conversations
明日来ない？
"Aren't you coming tomorrow?"
食べない？
"Won't you eat?"
3. Grammar Patterns
Many patterns require nai-form:
食べなくてもいい - don't have to eat
行かなければならない - must go
見ないで - without seeing
Conjugation Rules
Ichidan Verbs
Drop る, add ない:
食べる → 食べない (don't eat)
見る → 見ない (don't see)
寝る → 寝ない (don't sleep)
起きる → 起きない (don't wake up)
教える → 教えない (don't teach)
着る → 着ない (don't wear)
出る → 出ない (don't go out)
Godan Verbs
Change final -u sound to -a, then add ない:
買う → 買わない (kau → kawanai)
ka-u → ka-wanai
書く → 書かない (kaku → kakanai)
kak-u → kak-anai
読む → 読まない (yomu → yomanai)
yom-u → yom-anai
話す → 話さない (hanasu → hanasanai)
hanas-u → hanas-anai
待つ → 待たない (matsu → matanai)
mat-u → mat-anai
遊ぶ → 遊ばない (asobu → asobanai)
asob-u → asob-anai
帰る → 帰らない (kaeru → kaeranai)
kaer-u → kaer-anai
Special Case: う Verbs
う becomes わ + ない:
買う → 買わない (NOT 買あない)
言う → 言わない
会う → 会わない
歌う → 歌わない
Irregular Verbs
する → しない (don't do)
来る → 来ない (こない, konai) (don't come)
Special: ある
ある → ない (not exist)
(NOT あらない)
Complete Conjugation Chart
| Dictionary | A-row | Nai-form | Meaning |
|---|---|---|---|
| 書く | kak-a | 書かない | don't write |
| 読む | yom-a | 読まない | don't read |
| 話す | hanas-a | 話さない | don't speak |
| 待つ | mat-a | 待たない | don't wait |
| 遊ぶ | asob-a | 遊ばない | don't play |
| 死ぬ | shin-a | 死なない | don't die |
| 帰る | kaer-a | 帰らない | don't return |
| 泳ぐ | oyog-a | 泳がない | don't swim |
| 買う | kaw-a | 買わない | don't buy |
| 食べる | - | 食べない | don't eat |
| 見る | - | 見ない | don't see |
| する | - | しない | don't do |
| 来る | - | 来ない | don't come |
Present and Future Negative
Nai-form expresses both:
Present Habitual
私は肉を食べない
"I don't eat meat"
朝ご飯を食べない
"I don't eat breakfast"
お酒を飲まない
"I don't drink alcohol"
Future Negative
明日は行かない
"I won't go tomorrow"
今日は勉強しない
"I won't study today"
週末は働かない
"I won't work on the weekend"
Polite vs Plain Negative
| Plain (Nai) | Polite (Masen) | Meaning |
|---|---|---|
| 食べない | 食べません | don't eat |
| 行かない | 行きません | don't go |
| しない | しません | don't do |
| 来ない | 来ません | don't come |
| 見ない | 見ません | don't see |
Use nai-form in casual situations!
Common Patterns Using Nai-form
1. Don't Have To (～なくてもいい)
食べなくてもいい
"You don't have to eat"
行かなくてもいいよ
"You don't have to go"
勉強しなくてもいい
"You don't have to study"
2. Must (～なければならない / ～なきゃ)
勉強しなければならない
"I must study"
行かなきゃ
"I gotta go" (casual)
食べなきゃいけない
"I have to eat"
3. Without Doing (～ないで)
朝ご飯を食べないで学校に行った
"I went to school without eating breakfast"
何も言わないで帰った
"I left without saying anything"
4. If You Don't (～ないと)
急がないと！
"If we don't hurry! / We gotta hurry!"
勉強しないと試験に落ちる
"If you don't study, you'll fail the exam"
5. Negative Requests (～ないで)
行かないで
"Don't go"
泣かないで
"Don't cry"
忘れないで
"Don't forget"
Question Form
Use rising intonation:
食べない？
"Won't you eat? / Don't you eat?"
行かない？
"Won't you go? / Aren't you going?"
分からない？
"Don't you understand?"
Answering Negative Questions
Japanese yes/no can be tricky:
Q: 肉を食べない？
"Don't you eat meat?"
A: うん、食べない
"Right, I don't eat it"
(Agreeing with negative)
A: ううん、食べる
"No, I do eat it"
(Disagreeing with negative)
Common Mistakes
Mistake 1: Wrong A-row Conjugation
Wrong: 書く → 書くない ❌
Right: 書く → 書かない ✓
Wrong: 読む → 読むない ❌
Right: 読む → 読まない ✓
Mistake 2: う Verbs
Wrong: 買う → 買あない ❌
Right: 買う → 買わない ✓
Wrong: 言う → 言あない ❌
Right: 言う → 言わない ✓
Mistake 3: Using with Polite Suffix
Wrong: 食べないます ❌
Right: 食べません ✓ (polite)
Right: 食べない ✓ (plain)
Mistake 4: ある Exception
Wrong: あらない ❌
Right: ない ✓
時間がない
"There's no time"
Step-by-Step Conjugation
For Godan Verbs:
- Find the u-sound
- Change to a-sound
- Add ない
Example: 読む (yomu)
- u-sound: む (mu)
- a-sound: ま (ma)
- Result: 読まない (yomanai)
For Ichidan Verbs:
- Drop る
- Add ない
Example: 食べる (taberu)
- Drop る: 食べ
- Result: 食べない (tabenai)
Casual Conversation Examples
Example 1: Making Plans
A: 明日映画見ない？
"Want to see a movie tomorrow?"
B: ごめん、明日は行けない
"Sorry, I can't go tomorrow"
A: じゃあ、週末は？
"Then, how about the weekend?"
B: 週末はいいよ！
"The weekend is good!"
Example 2: Food Preferences
A: 納豆食べる？
"Do you eat natto?"
B: ううん、食べない。苦手
"No, I don't. I don't like it"
A: そうなんだ。じゃあ、寿司は？
"I see. Then, sushi?"
B: 寿司は好き！
"I like sushi!"
Example 3: Daily Habits
A: 毎日運動する？
"Do you exercise every day?"
B: ううん、しない。時々だけ
"No, I don't. Only sometimes"
A: そっか。僕も毎日はしない
"I see. I don't do it every day either"
With Frequency Words
ぜんぜん食べない
"I don't eat at all"
あまり飲まない
"I don't drink much"
ほとんど行かない
"I hardly go"
めったに見ない
"I rarely watch"
全く分からない
"I don't understand at all"
Common Expressions
知らない - don't know
分からない - don't understand
できない - can't do
いらない - don't need
いない - not here/don't exist (animate)
ない - not exist (inanimate)
Examples
それ知らない
"I don't know that"
意味が分からない
"I don't understand the meaning"
日本語ができない
"I can't speak Japanese"
お金がない
"I don't have money"
時間がない
"I don't have time"
Nai-form as Adjective
Nai-form conjugates like an い-adjective:
Present: 食べない
Past: 食べなかった
Te-form: 食べなくて
More on this in Nakatta Form.
Double Negatives
食べなくはない
"It's not that I don't eat" (= I do eat sometimes)
嫌いではない
"I don't dislike it" (= I kind of like it)
Nai-form in Compound Sentences
雨が降らないから、出かける
"Because it's not raining, I'll go out"
分からないので、教えてください
"I don't understand, so please teach me"
食べないけど、飲む
"I won't eat, but I'll drink"
Key Takeaways
✓ Nai-form = plain negative present/future
✓ Godan: change u→a + ない
✓ Ichidan: drop る + ない
✓ Irregular: する → しない, 来る → 来ない
✓ Special: ある → ない
✓ う verbs: う → わない
✓ Used in casual speech and grammar patterns
✓ Essential for intermediate grammar
Master nai-form - it's crucial for natural Japanese!
Next: Nakatta Form (Past Negative)
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