一段動詞與五段動詞：如何區分日語動詞的類別

Before you can conjugate a Japanese verb into the ます-form, the ない-form, the て-form, or anything else, you need to know which group it belongs to. Get the group wrong and every form you build will be wrong with it.

Different textbooks use different names for the groups, which causes plenty of confusion. Here is a quick key:

Step 1: Does it end in る?

If the verb does not end in る, it is godan. Full stop.

• 書く, 飲む, 話す, 買う, 待つ, 泳ぐ, 遊ぶ, 死ぬ — all godan.

This rule alone settles roughly half of the verbs you will meet.

Step 2: If it ends in る, look at the sound before it

For verbs ending in る, check the vowel in the kana right before る:

• If it is い or え (an -i or -e sound), the verb is probably ichidan.
  • 食べる (べ → え-row), 寝る (ね), 見る (み → い-row), 起きる (き).
• If it is あ, う, or お, the verb is godan.
  • 分かる (か → あ), 乗る (の → お), 取る (と → お), 作る (く → う).

Step 3: Learn the exceptions

Here is the catch. A small but important set of verbs end in -iru or -eru but are still godan. They look ichidan but conjugate as godan. The most common ones:

• 帰る (かえる) — to return home
• 入る (はいる) — to enter
• 走る (はしる) — to run
• 知る (しる) — to know
• 切る (きる) — to cut
• 要る (いる) — to need
• 散る, 減る, しゃべる, 蹴る, 限る, 握る

You do not need to memorize them all today. Start with 帰る, 入る, 走る, 知る, 切る, because those show up constantly. The rest will arrive through exposure.

Step 4: Memorize the two irregular verbs

• する (to do) and everything built from it: 勉強する, 散歩する, 結婚する.
• 来る (くる) (to come).

That is the full irregular list for everyday Japanese. A few honorific forms (いらっしゃる, おっしゃる) have their own quirks, which come up later; see keigo basics.

Why this matters

Compare what happens with the ない-form:

• 食べる (ichidan) → 食べない
• 飲む (godan) → 飲まない
• 帰る (godan exception) → 帰らない, not 帰ない

And the ます-form:

• 食べる → 食べます
• 飲む → 飲みます
• 帰る → 帰ります

For the て-form, see the rules in Japanese て-form conjugation made simple. The ichidan versus godan split is the foundation for every pattern there.

A practice routine

1. Sort a list. Take 20 verbs from your current vocabulary and label each G (godan), I (ichidan), or X (irregular). Check against a dictionary, which marks the group.
2. Conjugate one form. For each, write the ない-form. Errors reveal gaps immediately.
3. Keep the exceptions on a sticky list. Add any verb that surprised you. This is exactly the habit described in keep a JLPT mistake log.

What the JLPT tests

Group knowledge is rarely tested in isolation, but it underlies many questions:

• Choose the correct conjugated form to complete a sentence.
• Spot the incorrect form among four options.
• Understand the form in a reading or listening passage quickly.

At N5 and N4, being fluent in these conjugations gives you speed. When you do not have to think about the rules, you can spend your time on comprehension.

Reading vs writing in dictionaries

In Japanese dictionaries, verbs are often labeled 五段 / 上一段 / 下一段 / サ変 / カ変. 上一段 and 下一段 are both ichidan (the former ends in -iru, the latter in -eru). Knowing this label will help you read dictionary entries and grammar books.

Next steps

For the broader picture of what is needed for each level, the JLPT N5 grammar checklist is a good map, and the JLPT preparation guide shows how it all fits together. JLPT Ready's Learn chapters give plain-language explanations for each grammar item and link to practice questions that test it. You can start free with N5 and try it with no card required.