The Masu Form: Polite Japanese Verbs Made Simple

What the masu form is and why it matters

The masu form is the polite present tense of Japanese verbs, and it is the safe, respectful way to talk to anyone you are not close with. You build it from a verb stem plus ます (masu), and the result is a verb you can use with a stranger, a shopkeeper, a teacher, or a coworker without sounding too casual.

This is usually the first verb form Japanese courses teach, and there is a good reason for that. The masu form is polite, so you will rarely cause offense with it. It is regular, so once you learn the pattern you can apply it to thousands of verbs. And it lets you make real, complete sentences almost immediately, which means you can start saying useful things long before you have studied any grammar in depth.

There is a more casual register, called the plain or dictionary form, that you will meet later. But starting with the masu form gives you a polite default you can lean on in almost any situation. When you are unsure how formal to be, the masu form is the form that keeps you on safe ground.

The three verb groups

Every Japanese verb belongs to one of three groups, and the group decides how you conjugate it. There are no exceptions to this membership: each verb is a Group 1 verb, a Group 2 verb, or one of the two Group 3 irregulars. Once you know a verb's group, the masu form follows a fixed rule.

• Group 1 verbs are also called u-verbs or godan verbs. They are the largest group, and they are the ones that change their final sound before adding ます.
• Group 2 verbs are also called ru-verbs or ichidan verbs. They are the simplest to conjugate: you drop one syllable and add ます.
• Group 3 is just the two irregular verbs, する (suru) and くる (kuru). They do not follow either pattern, so you memorize them.

There is one honest catch worth flagging early. A small number of verbs that end in -eru or -iru look like they should be Group 2 ru-verbs, but they are actually Group 1. The example from this lesson is かえる (kaeru), to return. It ends in -eru, which makes it look like a ru-verb, but it conjugates as a Group 1 u-verb. There is no reliable way to spot these by sight, so the practical advice is simple: when you learn a new verb, learn which group it belongs to at the same time. That one habit removes almost all of the guesswork.

Group 1: u-verbs

To put a Group 1 verb into the masu form, change the final -u sound to its matching -i sound, then add ます. This is the group most learners find fiddly, so it is worth slowing down and seeing the logic behind it.

Japanese kana are organized into rows that share a consonant. Within a row, the vowel changes from -a to -i to -u to -e to -o. The dictionary form of a verb ends on the -u vowel of its row, and the masu stem simply steps back one place to the -i vowel of the same row. So the shift always stays inside the verb's own kana row:

Once that shift clicks, the masu form is just the changed sound plus ます. Here are the worked examples:

Notice that はなす (hanasu) becomes はなします (hanashimasu), not a naive "hanasimasu" with a plain "si" sound: the す row shifts to し (shi), so the romaji reflects the natural Japanese pronunciation. The same is true for まつ (matsu), where つ shifts to ち (chi), giving まちます (machimasu). And かえる (kaeru) sits at the bottom of the table on purpose: it ends in -eru and looks like a Group 2 verb, but it is Group 1, so its る shifts to り and it becomes かえります (kaerimasu).

Group 2: ru-verbs

To put a Group 2 verb into the masu form, drop the final る and add ます. There is no sound shift and no row logic to track, which makes this the easiest group of the three.

The pattern is consistent every time: たべる (taberu) loses its る and becomes たべます (tabemasu); みる (miru) becomes みます (mimasu); ねる (neru) becomes ねます (nemasu). The part that remains after you drop る is called the verb stem, and you will use that same stem for many other forms later, so it is a useful thing to recognize. The only thing to stay alert to is the catch from the previous section: some verbs that end in -eru or -iru, like かえる (kaeru), only look like this group and actually belong to Group 1.

Group 3: the two irregulars

Group 3 contains exactly two verbs, and you simply memorize them. They do not follow the Group 1 sound shift or the Group 2 drop-the-る rule, but because there are only two of them, they are quick to learn.

する (suru) becomes します (shimasu), and くる (kuru) becomes きます (kimasu). These two are worth the small effort to memorize because they show up constantly. する in particular attaches to many nouns to form verbs, so once you know it becomes します, a large number of everyday actions become easy to say politely.

The four masu endings: present, negative, past, past negative

Once a verb is in the masu form, four endings cover present, negative, past, and past negative, with no new rules to learn. This is the real payoff of the masu form. You find the stem once, and then you swap the ending depending on the meaning you want. Here are all four shown on たべる (taberu), to eat, whose stem is たべ (tabe):

Read down the list and you can see the system. The present affirmative uses ます (masu). The negative replaces it with ません (masen). The past uses ました (mashita). And the past negative is the negative ません followed by でした (deshita), giving ませんでした (masen deshita). The stem, たべ (tabe), never changes; only the ending after it does.

One detail worth noticing is that the Japanese present tense covers both "eat" and "will eat." Japanese does not separate present from future the way English does, so たべます (tabemasu) can mean either "I eat" or "I will eat" depending on context. The same applies to the negative: たべません (tabemasen) can mean "I do not eat" or "I will not eat." This is genuinely simpler than English, because there is one fewer tense to manage.

Because these four endings work identically on every verb once it is in masu form, the hard part of conjugation is really just finding the stem. After that, present, negative, past, and past negative are all the same four swaps, whether the verb is のむ (nomu), たべる (taberu), or する (suru).

How to practice conjugation

The calmest way to learn the masu form is to drill a small handful of verbs through all four endings until the pattern feels automatic, rather than trying to memorize hundreds of verbs at once. Pick a few you will actually use, perhaps のむ (nomu), たべる (taberu), and する (suru), and run each one through present, negative, past, and past negative out loud. Repetition on a few verbs teaches the system; the system then transfers to every other verb you meet.

When you learn a new verb, learn its group at the same time. This is the single habit that prevents the most common mistake, treating a Group 1 verb like かえる (kaeru) as if it were a Group 2 ru-verb. If the group is part of how you store the verb in your memory, the right conjugation comes with it.

Spaced repetition fits this kind of practice well, because it surfaces verbs again just as you are starting to forget them, which is exactly when reviewing them does the most good. If you would like the reviews handled for you, Inku is a calm iPhone flashcard app that uses FSRS spaced repetition and bundled audio, so you can hear each verb as it comes back to you. It covers kana through JLPT N4 vocabulary, works locally with no account and no ads, and stays out of your way while you study.

Once the masu form feels comfortable, the natural next step is the te-form, which is the connector that opens up requests, ongoing actions, and many compound structures in Japanese. It builds on the same group distinctions you have just learned, so the work you put into recognizing Group 1, Group 2, and Group 3 verbs here pays off directly. Take it slowly, keep your verb list short, and let the four endings become second nature before you move on.

Common questions

Related reading

• The te-form, the next conjugation to learn
• Japanese particles
• JLPT N5 vocabulary list
• Japanese verbs
• N5 verbs vocabulary
• Keigo (honorific speech)

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