How to Say Must in Japanese – 8 Must-Know Grammar Rules.

How do you say must in Japanese?

Or “I have to…” in Japanese? Well, glad you asked.

In this “How to Say Must in Japanese” guide, you’ll learn 7 “must” grammar rules, include explanations and TONS of examples. So that these rules get drilled into your head.

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So, if you want to learn Japanese, you must read this guide.

Must! Get it? Must? Good, right?


Rule #1 Verb + Beki da

“Beki da” is a way to say should…or say must in Japanese.

All you need is the dictionary form of the verb and add べきだ (beki da) to the end. One exception to this rule is the verb “to do” or する (suru) and it can appear as するべきだ (suru beki da) or すべきだ (su beki da). If you’d like to make this more formal, replace べきだ (beki da) with べきです (beki desu). In Japanese, “should” statements could sound rude if used in the wrong context. Make sure you know the other person well or use it to talk about yourself.

  • 学校に行くべきだ。
    • Gakkou ni iku beki da.
    • You should go to school.
  • わたしは本を返すべきだ。
    • Hon o kaesu beki da.
    • I should return the book.
  • 謝るべきだ。
    • Ayamaru beki da.
    • You should apologize.
  • 感謝すべきだ。
    • Kansha su beki da.
    • You should be grateful.
  • 高校を卒業すべきだ。
    • Koukou o sotsugyou su beki da.
    • You should graduate from high school.

Rule #2 Nakute wa ikenai

This is the most common way to say must in Japanese…

…And if you’re learning in a class or from a textbook, then this is what you’ll learn first.

“Nakute wa ikenai” is similar to nakereba narimasen” (see below), but it is slightly less formal. The way that the grammar is formed is also by using nai form verbs. ない (nai), the ending of a nai form verb, changes to なくてはいけない (nakute wa ikenai). This grammar form means “must” or “have to” and appears frequently in writing. There is also a polite form where なくてはいけない (nakute wa ikenai) changes to なくてはいけません (nakute wa ikemasen).

  • 早く寝なくてはいけない。
    • Hayaku nenakute wa ikenai.
    • I must go to bed early.
  • 車を洗わなくてはいけない。
    • Kuruma o arawanakute wa ikenai.
    • I must wash my car.
  • 日本語を学ばなくてはいけない。
    • Nihongo o manabanakute wa ikenai.
    • I must learn Japanese.
  • もっと本を読まなくてはいけない。
    • Motto hon o yomanakute wa ikenai.
    • I must read more books.
  • 買い物に行かなくてはいけない。
    • Kaimono ni ikanakute wa ikenai.
    • I must go shopping.

Rule #3 Nakereba naranai

This grammar rule is most often encountered in writing.

Japanese people prefer to use shorter forms that mean “have to” or “must” in their speech. In particular, nakereba naranai is used for rules that everyone must follow. To form this grammar, you can take a nai form verb and drop the い (i) and add ければならない (kereba naranai). For a more polite form, you can change ならない (naranai) to なりません (narimasen).

  • 電車の中では静かにしなければならない。
    • Densha no nakade wa shizuka ni shinakereba naranai.
    • One must be quiet inside the train.
  • 宿題は毎日しなければならない。
    • Shukudai wa mainichi shinakereba naranai.
    • One must do homework every day.
  • 学校で制服を着なければならない。
    • Gakkou de seifuku o kinakereba naranai.
    • One must wear a uniform at school.
  • 街の中ではゆっくり運転をしなければならない。
    • Machi no nakade wa yukkuri unten o shinakereba naranai.
    • One must drive slowly inside the town.
  • ゴミはきちんと捨てなければならない。
    • Gomi wa kichinto sute nakereba naranai.
    • One must throw away trash properly.

Rule #4 Naito

Naito is a casual way to say “have to” that can be formed with verbs in the nai form. Just add a と(to) to the end of the verb. For example, the verb  飲む (nomu) becomes 飲まない (nomanai) in the nai form. It then changes to 飲まないと (nomanaito). This grammar rule usually indicates that you have to do something soon or quickly.

  • もう行かないと。
    • Mou ikanaito.
    • I have to go already.
  • 早く食べないと。
    • Hayaku tabenaito.
    • I have to eat quickly.
  • 掃除しないと。
    • Souji shinaito.
    • I have to clean.
  • 洗濯しないと。
    • Sentaku shinaito.
    • I have to do laundry.
  • 早く家に帰らないと。
    • Hayaku ie ni kaeranaito.
    • I have to go home soon.

Rule #5 Nakucha / Nakya

This grammar rule is similar to naito but it’s more colloquial. Nai form verbs are changed to なくちゃ (nakucha) or なきゃ (nakya) by dropping い (i) and adding くちゃ (kucha) or (きゃ). Both nakucha and nakya can be used to mean the same thing. Instead of “have to”, it might be more like “gotta” in casual English.

  • 宿題しなきゃ。
    • Shukudai shinakya.
    • I gotta do my homework.
  • メール書かなくちゃ。
    • Meeru kakanakucha.
    • I gotta write an email.
  • ご飯作らなきゃ。
    • Gohan tsukuranakya.
    • I gotta make food.
  • 仕事しなきゃ。
    • Shigoto shinakya.
    • I gotta work.
  • 銀行に行かなくちゃ。
    • Ginkou ikanakucha.
    • I gotta go to the bank.

Rule #6 Naito ikenai

This grammar rule means “have to” or “must”. It’s usually used as a way to express something you feel an obligation to do. Using a verb’s nai form, you can create sentences with this grammar. For example, 食べる(taberu), “to eat”, becomes 食べないといけない (tabenaito ikenai) or “I have to eat”.

  • 明日運動しないといけない。
    • Ashita undou shinaito ikenai.
    • I have to exercise tomorrow.
  • 来週は仕事をしないといけない。
    • Raishuu wa shigoto o shinaito ikenai.
    • I have to work next week.
  • もっと勉強しないといけない。
    • Motto benkyou shinaito ikenai.
    • I must study more.
  • 病院に行かないといけない。
    • Byouin ni ikanaito ikenai.
    • I must go to the hospital.
  • 家賃を払わないといけない。
    • Yachin o harawanaito ikenai.
    • I have to pay the rent.

Rule #7 Naito dame

Naito dame works like naito ikenai and means “have to” or “must”. Nai form verbs can easily be changed to naito dame by adding とだめ (to dame). For example, 飲まない (nomanai) becomes 飲まないとだめ (nomanaito dame). Unlike some of the other grammar rules, this one can be used for yourself or parents might say it to their children when they “must” do something.

  • 野菜を全部食べないとだめ。
    • Yasai o zenbu tabenaito dame.
    • You have to eat all the vegetables.
  • 手伝わないとだめ。
    • Tetsudawanaito dame.
    • You have to help.
  • 私は今日までに読まないとだめ。
    • Watashi wa kyou made ni yomanaito dame.
    • I have to read by today.
  • 薬を飲まないとだめ。
    • Kusuri o nomanaito dame.
    • You must take the medicine.
  • 私は明日早起きしないとだめ。
    • Watashi wa ashita hayaoki shinaito dame.
    • I have to wake up early tomorrow.


Now you know how to say must in Japanese. Here’s a quick recap of the patterns:

  1. Beki da
  2. Naito ikenai
  3. Naito dame
  4. Nakucha / Nakya
  5. Naito dame
  6. Nakereba naranai
  7. nakute wa ikenai

Re-read and write out the example sentences above to help make the grammar rules stick.

And of course, use them.

Either way, thanks for reading and for learning Japanese with Linguajunkie.

– The Main Lingua Junkie

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