Master the ない (Nai) Form: Plain Negative Verbs (JLPT N4)

Welcome to your definitive guide to the ない (Nai) form. If you want to speak casual Japanese, express obligations, or give polite prohibitions, mastering this form is non-negotiable.

In polite Japanese, you use 〜ません (-masen) to negate verbs. In casual speech, and as a building block for advanced grammar, we use the Plain Negative (ない) form.

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1. How to Conjugate Verbs into the ない Form

To conjugate correctly, you must first identify which of the three verb groups your verb belongs to.

Group 1: Godan Verbs (U-Verbs)

Rule: Change the final dictionary hiragana character from the 〜u row to its corresponding character in the 〜a row, then add ない.

• Crucial Exception: If the verb ends in a hiragana う (u), change it to わ (wa), not あ (a).

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Group 2: Ichidan Verbs (Ru-Verbs)

Rule: Simply drop the final る (ru) and add ない.

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Group 3: Irregular Verbs & Special Cases

There are only two irregular verbs, plus one highly important exception you must memorize.

• する (to do) $\rightarrow$ しない (shinai)
• 来る (くる - to come) $\rightarrow$ 来ない (こない - konai) (Note the pronunciation change from "ku" to "ko"!)来
• ある (to exist/have) $\rightarrow$ ない (nai) (Do not say "aranai")

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2. Essential N4 Grammar Patterns Using the ない Form

The ない form is the foundation for several vital N4 grammar structures. Here are the three most common:

Pattern A: 〜ないでください (Please don't...)

Used to politely request that someone refrain from doing something.

• Form: Verb [ない Form] + でください
• Example:
  • 写真を撮らないでください。写真撮
  • Shashin o toranaide kudasai.
  • Please do not take photos.
  写真撮

Pattern B: 〜なければなりません (Must / Have to)

Used to express obligation. To form this, drop the final い from the ない form and add ければなりません.

• Form: Verb [な] + ければなりません
• Example:
  • 薬を飲まなければなりません。薬飲
  • Kusuri o nomanakereba narimasen.
  • I must take my medicine.
  薬飲

Pattern C: 〜なくてもいいです (Don't have to...)

Used to grant permission not to do something. Drop the final い from the ない form and add くてもいいです.

• Form: Verb [な] + くてもいいです
• Example:
  • 靴を脱がなくてもいいです。靴脱
  • Kutsu o nuganakute mo ii desu.
  • You don't have to take off your shoes.
  靴脱

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Quick Challenge!

Can you translate this sentence into Japanese using what you learned?

"Please do not write in the textbook."
(Hint: Textbook is 教科書 - kyōkasho; to write is 書く - kaku)教科書

Answer: 教科書に書かないでください。(Kyōkasho ni kakanaide kudasai.)教科書