Verb groups and the polite ます-form
A1 動詞の種類とます形（ます・ません・ました・ませんでした） 7 / 69
In short
Every Japanese verb belongs to one of three groups, and the group tells you how to cut the dictionary form down to its ます-stem. Onto that stem you snap one of exactly four polite endings: ます (non-past), ません (non-past negative), ました (past), ませんでした (past negative). The verb always comes last in the sentence.
The rule
Japanese verbs do not change for person or number - there is no “I go / he goes”. All the work happens at the end of the word, and the sentence is built Subject - Object - Verb (SOV): 私はパンを食べます (Watashi wa pan o tabemasu, “I eat bread”). Whatever else you add, the verb closes the sentence.
To build the polite form, work in three steps.
Step 1 - Identify the group. Dictionaries list verbs in the dictionary form (辞書形), which always ends in the vowel -u.
- Group I (五段動詞, “godan”, u-verbs) - everything that ends in something other than る: 書く kaku, 話す hanasu, 飲む nomu, 買う kau, 待つ matsu. Plus many verbs that do end in る.
- Group II (一段動詞, “ichidan”, ru-verbs) - the stem ends in the vowel -e or -i and then る: 食べる taberu, 見る miru, 起きる okiru, 寝る neru.
- Group III - two irregulars only: する suru (“do”) and 来る kuru (“come”).
The only genuinely tricky case is a verb ending in る. If the vowel before る is a, u or o (作る tsukuru, 乗る noru, 分かる wakaru), it is always Group I. If the vowel is e or i, it is usually Group II - but a small set of very common verbs are Group I traps and must be memorised:
帰る kaeru (go home), 入る hairu (enter), 走る hashiru (run), 知る shiru (know), 切る kiru (cut), 要る iru (need).
Step 2 - Make the ます-stem (ます形の語幹, also called 連用形).
- Group I: change the final -u to -i, staying inside the same kana column: 書く -> 書き kaki, 飲む -> 飲み nomi. Watch the two kana whose consonant changes in romaji: つ -> ち (tsu -> chi) and す -> し (su -> shi). A 〜う verb simply takes い: 買う -> 買い kai.
- Group II: just drop る: 食べる -> 食べ tabe, 見る -> 見 mi.
- Irregulars: する -> し shi, 来る -> 来 ki. Note that the kanji 来 is read ku in 来る but ki in 来ます - the kanji stays, the reading moves.
Step 3 - Attach one of the four endings. The pattern is ます-stem + ます / ません / ました / ませんでした. Nothing else changes, in any group.
Two tenses, four cells. Japanese has a non-past and a past, not a present and a future. 行きます covers both “I go (regularly)” and “I will go (tomorrow)”; context or a time word decides. Likewise ました covers “ate” and “have eaten”. The negative past is ませんでした - a frozen unit, never ×ませんだった.
The stem is a building block. The ます-stem is not only for ます. It is the attachment point for 〜たい (want to), 〜ながら (while), 〜すぎる (too much), 〜方 (way of doing) and compound verbs like 飲み始める (start drinking). Learning the stem now pays for itself for the next sixty lessons.
Forms & patterns
Group I: the final -u moves to the -i row.
| Dictionary ending | Shift | Example | ます-form |
|---|---|---|---|
| 〜う | う -> い | 買う kau (buy) | 買います kaimasu |
| 〜く | く -> き | 書く kaku (write) | 書きます kakimasu |
| 〜ぐ | ぐ -> ぎ | 急ぐ isogu (hurry) | 急ぎます isogimasu |
| 〜す | す -> し | 話す hanasu (speak) | 話します hanashimasu |
| 〜つ | つ -> ち | 待つ matsu (wait) | 待ちます machimasu |
| 〜ぬ | ぬ -> に | 死ぬ shinu (die) | 死にます shinimasu |
| 〜ぶ | ぶ -> び | 遊ぶ asobu (play) | 遊びます asobimasu |
| 〜む | む -> み | 飲む nomu (drink) | 飲みます nomimasu |
| 〜る | る -> り | 作る tsukuru (make) | 作ります tsukurimasu |
The four-cell polite paradigm.
| Group I 書く kaku | Group II 食べる taberu | する suru | 来る kuru | |
|---|---|---|---|---|
| ます-stem | 書き kaki | 食べ tabe | し shi | 来 ki |
| Non-past | 書きます kakimasu | 食べます tabemasu | します shimasu | 来ます kimasu |
| Non-past negative | 書きません kakimasen | 食べません tabemasen | しません shimasen | 来ません kimasen |
| Past | 書きました kakimashita | 食べました tabemashita | しました shimashita | 来ました kimashita |
| Past negative | 書きませんでした kakimasen deshita | 食べませんでした tabemasen deshita | しませんでした shimasen deshita | 来ませんでした kimasen deshita |
Core verbs to memorise with their group tag.
| Verb | Romaji | Group | ます-form | Meaning |
|---|---|---|---|---|
| 行く | iku | I | 行きます | go |
| 読む | yomu | I | 読みます | read |
| 聞く | kiku | I | 聞きます | listen, ask |
| 会う | au | I | 会います | meet |
| 帰る | kaeru | I (trap) | 帰ります | go home |
| 入る | hairu | I (trap) | 入ります | enter |
| 走る | hashiru | I (trap) | 走ります | run |
| 知る | shiru | I (trap) | 知ります | come to know |
| 見る | miru | II | 見ます | see, watch |
| 起きる | okiru | II | 起きます | get up |
| 寝る | neru | II | 寝ます | sleep, go to bed |
| 教える | oshieru | II | 教えます | teach |
| する | suru | III | します | do |
| 勉強する | benkyō suru | III | 勉強します | study |
| 来る | kuru | III | 来ます | come |
Examples
- 私は毎朝コーヒーを飲みます。 (Watashi wa maiasa kōhī o nomimasu.) - I drink coffee every morning.
- あした学校へ行きます。 (Ashita gakkō e ikimasu.) - I am going to school tomorrow.
- 田中さんは今日来ません。 (Tanaka-san wa kyō kimasen.) - Mr Tanaka is not coming today.
- きのう友達と映画を見ました。 (Kinō tomodachi to eiga o mimashita.) - Yesterday I watched a film with a friend.
- 先週は日本語を勉強しませんでした。 (Senshū wa Nihongo o benkyō shimasen deshita.) - I did not study Japanese last week.
- 父は六時に帰ります。 (Chichi wa roku-ji ni kaerimasu.) - My father comes home at six.
- 駅から家まで歩きます。 (Eki kara ie made arukimasu.) - I walk from the station to my house.
- 山田さんは毎日新聞を読みます。 (Yamada-san wa mainichi shinbun o yomimasu.) - Mr Yamada reads the newspaper every day.
- 今晩レストランで食べます。 (Konban resutoran de tabemasu.) - We are eating at a restaurant tonight.
Common mistakes
- 飲むます (nomumasu) -> 飲みます (nomimasu) - ます never attaches to the dictionary form. Cut to the stem first: 飲む -> 飲み.
- 帰ます (kaemasu) -> 帰ります (kaerimasu) - 帰る ends in -eru but is a Group I trap, so the る becomes り, it is not dropped. Same for 入る, 走る, 知る.
- 見ります (mirimasu) -> 見ます (mimasu) - 見る is genuinely Group II; do not apply the Group I -u -> -i shift to it.
- 来ります (kirimasu) -> 来ます (kimasu) - 来る is irregular: the whole る goes and the reading changes to ki.
- 私は食べますパンを。 (Watashi wa tabemasu pan o.) -> 私はパンを食べます。 (Watashi wa pan o tabemasu.) - Japanese is verb-final. Objects and time words come before the verb, never after it.
Tips
- Learn every new verb as a pair: dictionary form + ます-form (飲む／飲みます). The pair alone tells you the group, so you never have to guess later. Japanese dictionaries also tag it directly: 五段 = Group I, 上一段／下一段 = Group II.
- Group II is the smaller of the two big classes, and every one of its members ends in -iru or -eru. So the working default is: if it does not end in -iru/-eru, it is Group I; if it does, it is probably Group II - unless it is one of the Group I traps listed above.
- There is no future tense. Do not hunt for a word meaning “will”: 行きます already means “I will go”. A time word (あした ashita “tomorrow”, 毎日 mainichi “every day”) does the disambiguating.
- Many ます-stems are also nouns you already need: 休む yasumu (rest) -> 休み yasumi (a holiday), 話す hanasu (speak) -> 話 hanashi (a story). Free vocabulary from grammar you already know.