Verb Conjugation「買う(かう、kau)」buy, will buy | Learn Japanese Grammar

Japanese verbs have conjugations.「買う(かう、kau)」is a verb and means “buy” or “will buy.” We will teach you the conjugation on this page. You can also learn example sentences using verb conjugations.

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When you do not know how to use the conjugation, please learn about it in our conversation lessons or our mail support. In our mail support, we check your Japanese every time. If you have an internet connection and a PC/smartphone, you can learn Japanese with us all over the world.
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Vocabulary Video

Before you learn the conjugations, please learn about the pronunciation of the verb in dictionary and ます forms.

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Dictionary Form/ます Form

As you know, English tenses are roughly divided into present, future, and past tenses. However, it is said that Japanese tenses consist only of “Past Tense” and “Non-Past Tense.” Therefore, we used “Dictionary Form,” not “Present Tense” in this heading.
Japanese people use two types of language. One is “non-honorific language” and the other is “honorific language.” When we focus on these languages, “dictionary” and “plain” forms are in “non-honorific language.” “Polite form” is in honorific language.

English Meaning: buy, will buy

PositiveConjugationRomaji Reading
Dictionary & Plain Formkau
ます & Polite Formいますkaimasu

辞書じしょけい (dictionary form)」is the original form. The technical term is for non-native Japanese speakers. Therefore, native Japanese usually do not know the word.「ますけい (ます form)」is the polite form of a dictionary form. The term is also for non-native Japanese speakers.

I’ll buy a washing machine tomorrow morning.

明日あした午前中ごぜんちゅう洗濯機せんたくきを買う。 (Plain Form)
明日、午前中に洗濯機を買います。(Polite Form)

English Meaning: do not buy, will not buy

NegativeConjugationRomaji Reading
Plain Formわないkawanai
Polite Form買いませんkaimasen

I won’t buy a washing machine this year.

今年ことし洗濯機せんたくきを買わない。(Plain Form)
今年は洗濯機を買いません。(Polite Form)

Past Tense

English Meaning: bought

The plain form is in “た form”. “た form” is also a technical term for non-native Japanese speakers. Therefore, native Japanese usually do not know the word.

PositiveConjugationRomaji Reading
た & Plain Formったkatta
Polite Form買いましたkaimashita

My father bought a car yesterday.

昨日きのうちちくるまを買った。(Plain Form)
昨日、父が車を買いました。(Polite Form)

English Meaning: did not buy

NegativeConjugationRomaji Reading
Plain Formわなかったkawanakatta
Polite Form買いませんでしたkaimasen deshita

My father didn’t buy a car yesterday.

昨日きのうちちくるまを買なかった。(Plain Form)
昨日、父は車を買いませんでした。(Polite Form)

て Form

English Meaning: N/A

We cannot know the exact meaning without knowing the sentence and situation.

ConjugationRomaji Reading
て Formってkatte

About the phrases「ている」and「ています」: Here
About the phrase「~てください。」: Here


I bought a cake and went to my friend’s house.

ケーキを買って、友達ともだちいえきました。(Polite Form)

In this case,「て」indicates “and” or “after.”

Volitional Form 1: Will, (Own) Intention, Determination

English Meaning: will buy

ConjugationRomaji Reading
Plain Formおうkaō
Polite FormN/AN/A

This phrase is used only in plain form. This is because we use it when we talk to ourselves or think in our minds. When we talk or think to ourselves, we usually do not use the polite form.

I’ll buy a bicycle next month.

来月らいげつ自転車じてんしゃを買おう。(Plain Form)

Volitional Form 2: Solicitation, Intention, Invitation

English Meaning: let’s buy

ConjugationRomaji Reading
Plain Formおうkaō
Polite Form買いましょうkaimashō

Let’s buy some crepes in Harajuku!

原宿はらじゅくでクレープを買おう。(Plain Form)
原宿でクレープを買いましょう。(Polite Form)

Imperative Form

English Meaning: buy! (order, command)

PositiveConjugationRomaji Reading
Plain Formkae

Buy these shoes!

このくつを買え。(Plain Form)

“Imperative form” is used only in plain form and this phrase often becomes rude depending on the situation. Please show us your Japanese when you use it. We will check and teach suitable Japanese.
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Prohibition and Order

English Meaning: do not buy!

NegativeConjugationRomaji Reading
Plain Formうなkauna

Don’t buy expensive things!

たかものを買うな。(Plain Form)

Conditional Form

English Meaning: if (subject) buy

ConjugationRomaji Reading
えばkaeba

If you buy a fan, it will be cooler.

扇風機せんぷうきを買えば、すずしくなるでしょう。(Polite Form)

Hypothetical/Definite Conditions, Sequence of Actions

English Meanings: if/when ~ buy, ~ bought and ~

The form「~たら」has different usages. It has other meanings except from those listed above. More explanations are in our conversation lessons or mail support.

ConjugationRomaji Reading
ったらkattara

Here is an example sentence wherein「たら」indicates a “sequence of actions.”

I bought a new microwave and cooking became easier.

あたらしい電子でんしレンジを買ったら、料理りょうりらくになりました。(Polite Form)

Causative Form

English Meaning: make/let/have (person) buy

PositiveConjugationRomaji Reading
Plain Formわせるkawaseru
Polite Form買わせますkawasemasu

I’ll let my boyfriend buy our wedding ring.

彼氏かれし結婚指輪けっこんゆびわを買わせる。(Plain Form)
彼氏に結婚指輪を買わせます。(Polite Form)

English Meaning: do not make/let/have (person) buy

NegativeConjugationRomaji Reading
Plain Formわせないkawasenai
Polite Form買わせませんkawasemasen

I won’t let my son buy alcohol.

息子むすこにおさけを買わせない。 (Plain Form)
息子にお酒を買わせません。(Polite Form)

Potential Verb

可能かのう動詞どうし (potential verb/s)」is a verb classification that indicates “be able to” or “can do something.”「書ける(かける、kakeru)」is one of the potential verbs.「書く」and「書ける」are different verbs in Japanese. The details of the potential verb「書ける」is here:

To Learn Correct Verb Conjugations

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Verb Conjugation