Masu form in Japanese: ます, ません, ました and ませんでした

THE masu shape is the most important polite standard for starting to conjugate verbs in Japanese. It organizes four basic combinations: ます in the non-past affirmative, ません in the non-past negative, ました in the past affirmative, and ませんでした in the negative past.

These endings appear frequently in classes, customer service, work, and conversations with people you don't know well yet. “Non-past” is the most precise term because the same form can indicate habitual present or future, depending on the context.

What is the masu form?

The masu form is the polite form of verbs. It allows you to affirm or negate an action in the non-past and past without having to reconstruct the verb in each sentence. The Marugoto's chart of polite and simple forms, from the Japan Foundation, organizes exactly these four combinations.

The ending expresses politeness, tense, and affirmation or negation. The lexical meaning remains in the verb: 食べ means “to eat,” while the final part informs how that action is presented.

When to use the polite style in Japanese

Japanese alternates between polite and plain styles depending on the relationship between people and the situation. The Irodori explanation about speech styles shows the use of です and ます with people you're not close to, on first encounters, or when speaking to someone hierarchically superior.

This doesn't mean the masu form is limited to ceremonies or very formal settings. For a beginner, it works as a polite and safe register in many everyday interactions. In a conversation between close friends, the plain form of verbs may sound more natural; in customer service or a conversation with strangers, the polite form is usually the appropriate choice.

It's also important to separate politeness from honorific language. Ending a verb with ます makes the sentence polite, but it doesn't automatically turn the vocabulary into keigo.

How to form ます in each verb group

Before conjugating, identify whether the verb is godan, ichidan, or irregular. If this classification still causes doubt, review the Verb groups in Japanese. The ending in る, by itself, is not enough to decide the group.

Godan verbs: move from the U line to the I line

In godan verbs, replace the last kana with the corresponding form from the I line and add ます. This procedure produces the base used by all polite endings.

Ichidan verbs: remove る

For ichidan verbs, remove the final る and add ます: 食べる → 食べます, 見る → 見ます, and 起きる → 起きます. Do not apply this rule automatically to every verb ending in -iru or -eru: 帰る, 入る, and 走る, for example, are godan.

Irregular verbs

The two central patterns of the irregular group are stable: する becomes します, and 来る (くる, kuru) becomes 来ます (きます, kimasu). In compound verbs with する, the same transformation is maintained: 勉強する → 勉強します.

O Marugoto's verb conjugation appendix allows you to compare the ます form, the stem without ます, and the dictionary, て, た, and ない forms across the three groups.

How to form ません, ました, and ませんでした

After finding the stem, choose the ending that combines tense and polarity. There is no need to memorize a different rule for each group: the difference between the groups lies in forming the stem; the four polite endings are regular.

The stem without ます also participates in other structures. The Irodori shows the ます stem before 方, as in 書き方, “way of writing”. This helps you realize that 書き is a useful stem, not an independent complete word.

The non-past can indicate present or future

食べます does not correspond only to “I eat.” Depending on a time expression or the situation, it can also mean “I will eat.” Japanese does not create a separate future ending in this paradigm.

I drink coffee every morning.
Every morning, I drink coffee.
Maiasa, I'll have a kōhī.
I drink coffee every morning.

Tomorrow, I will go to the library.
Ashita, toshokan e ikimasu.
Tomorrow, I will go to the library.
Tomorrow, I will go to the library.

Today, I will not eat meat.
Kyō wa niku o tabemasen.
Today, I will not eat meat.
Today, I will not eat meat.

The expressions 毎朝, 明日, and 今日 guide the interpretation. Without context, the non-past form remains compatible with habits and general facts as well as future actions.

How to use the masu form in sentences

In an independent clause, the verb usually appears at the end. Particles continue to mark the relationships between elements; the guide on how to form sentences in japanese deepens that organization.

Yesterday, I studied Japanese.
Kinō, nihongo o benkyō shimashita.
Yesterday, I studied Japanese.
Yesterday, I studied Japanese.

Last Sunday, I did not work.
Senshū no nichiyōbi wa hatarakimasen deshita.
Last Sunday, I did not work.
Last Sunday, I did not work.

Mini dialogue

A: Do you study Japanese every day?
Do you study Japanese every day?
Mainichi, nihongo o benkyō shimasu ka?
Do you study Japanese every day?

B: Yes, I study. But yesterday I didn't study.
Yes, I study. But yesterday I didn't study.
Hai, benkyō shimasu. Demo, kinō wa benkyō shimasen deshita.
Yes, I study. But yesterday I didn't study.

The masu form and the plain form do not always occupy the same position

The masu form is appropriate for ending the predicate of a clause in polite style. Before a noun, however, the plain form is used: 日本で働く人です means “a person who works in Japan”. The sequence 働きます人 does not work in that position.

Therefore, a polite sentence can contain a plain form within it and end in です or ます. This difference avoids the mistaken idea that all verb forms in a sentence need to receive ます.

Common mistakes when conjugating the masu form

• Calling ます just present tense: it belongs to the non-past and can also indicate future.
• Removing る from every verb: 帰る is godan, so the form is 帰ります, not a form based on 帰.
• Forgetting the change う → い: 買う becomes 買います, not a sequence with わ.
• Using ます before nouns: clauses that qualify nouns normally require the plain form.
• Forming the negative past as ませんだった: the polite pattern taught here is ませんでした.
• Confusing politeness with honorific: ます marks polite style, but does not replace choices specific to keigo.

Conjugation exercise

1. Transform 書く into the non-past affirmative polite form.
2. Transform 食べる into the non-past negative polite form.
3. Transform する into the past affirmative polite form.
4. Transform 来る into the past negative polite form.
5. Transform 帰る into the non-past negative polite form.

Summary and next steps

To use the masu form, make three choices: identify the verb group, find the base, and select one of the four endings. Use ます and ません in the non-past; use ました and ませんでした in the past. Then, confirm whether the situation calls for polite style and note where the plain form is still needed. To place these choices within the larger language system, also review the Basics of Japanese Grammar.

With this base mastered, move on to the て form of verbs, used in many constructions, and the ましょう form, which uses the same base to make proposals like “let's do.”.