Negative ない: Formation Table

The plain negative 〜ない is the casual "not / don't," and — like the ます-stem — it is built on a single stem, the 未然形（みぜんけい, "irrealis stem"）. For 五段 verbs that stem is the あ-row: 書く → 書か → 書かない. Two things make this form worth its own page: the 五段 -う subclass hides a わ where you would expect nothing (会う → 会わない, not ×会あない), and one verb, ある, throws out its regular negative entirely and replaces it with the bare word ない. This page is the formation reference for all of it, anchored on 書く → 書かない.

五段: move to the あ-row, then add ない

For every 五段 verb, drop to the あ-row of the same consonant column and attach ない. 書く sits on the k-column, so its あ-row form is 書か, and the negative is 書かない.

The わ trap: -う verbs are not 〜あない

Look again at the last row. The あ-row of the あ-column should be あ itself, which would predict ×会あない — but the あ-row of a vowel-stem verb is spelled わ, a fossil of the older w that these verbs once carried (会う was historically aw-). So every -う verb takes わ before ない: 会う → 会わない, 買う → 買わない, 言う → 言わない, 使う → 使わない. This わ appears only in the negative-family stem — the te-form (会って), the ます-form (会います), and the past (会った) never show it.

一段 and the irregulars

一段 verbs are the easy case: drop る, add ない. 食べる → 食べない, 見る → 見ない, 起きる → 起きない. No row-shifting, because 一段 verbs have no consonant stem to move.

する → しない, and 来る → 来ない, read konai (the こ-row) — the same reading shift you see in 来た (kita) and 来る (kuru). These two are irregular; memorize them.

The big one: ある → ない (suppletive)

ある（"to exist / to have," for inanimate things）does not form a regular negative. You would expect ×あらない — but it does not exist in modern Japanese. Instead ある is replaced wholesale by the standalone word ない. This is suppletion: an entirely different word filling the negative slot, the way English "go" borrows "went." Contrast this with いる（existence of animate things）, which is a perfectly regular 一段 verb: いる → いない.

Two things trip English speakers here. First, English has one verb of existence ("there is / are") for people and things alike, so the ある／いる split feels arbitrary — but it is rigid: use いる for anything that moves under its own power (people, animals) and ある for everything else, and their negatives follow suit (いない vs ない). Second, English negates existence with a separate word ("isn't / aren't"), so learners reach for a "regular" negative of ある and produce ×あらない. There isn't one. ある's negative slot is simply the word ない — the same suppletion English itself uses in "go / went," where the past is a completely unrelated word rather than a predictable inflection.

Past-negative: ない → なかった

Because 〜ない behaves exactly like an い-adjective, its past is formed the い-adjective way: drop い, add かった. So 書かない → 書かなかった, 食べない → 食べなかった, しない → しなかった, 来ない → 来なかった, and ない → なかった.

Register

Plain 〜ない is the casual negative; its polite counterpart is 〜ません (書きません). As with all plain forms, ない still appears inside polite sentences — before nouns (行かない人), before から・と・ので, and before こと・の — because embedded clauses take the plain form regardless of the sentence's overall politeness. There is also an older literary/formal negative, 〜ぬ／〜ず (行かぬ, 行かず), covered on the classical negative page; in everyday modern Japanese, ない is the default.

Common mistakes

Key takeaways

• 五段 negative = あ-row stem + ない: 書かない, 読まない, 待たない, 取らない.
• The -う subclass takes わ: 会わない, 買わない, 言わない — never ×会あない (a fossil w).
• 一段 drops る + ない (食べない); する → しない, 来る → 来ない（こない）.
• ある → ない is suppletive (no ×あらない); animate いる → いない is regular.
• 〜ない conjugates like an い-adjective, so the past-negative is なかった (書かなかった).