Should be with 〜べきだ
Grammar: Necessity » 〜べき
〜べきだ says that someone ought to do something or that a situation should be a certain way. It carries more force than advice, but it stops short of a rule someone must obey.
The speaker presents a personal judgment about the proper action, so 〜べきだ can reflect the speaker’s values.
Usage
べきだ attaches to the dictionary form of a verb. Speakers use it to state what someone else should do, not what they themselves should or plan to do. In past tense, speakers can use it for something they think they should have done.
Formation
- Verb (dictionary form) + べきだ
- 約束は守
( るべきだ - "One should keep promises."
- 約束は守
- す(る) + べきだ
- もっと練習す(る)べきだ
- "You should practice more."
- Note: You may see either するべき or the more common すべき.
- Verb (dictionary form) + べきではない (negative)
- 嘘
( をつくべきではない - "You shouldn't tell lies."
- 嘘
- Verb (dictionary form) + べきじゃない (casual negative)
- そんなこと言
( うべきじゃないよ - "You shouldn't say something like that."
- そんなこと言
- Verb (dictionary form) + べきだった (past)
- もっと早
( く謝( るべきだった - "I should have apologized sooner."
- Note: The past form can carry a sense of regret.
- もっと早
- Verb (dictionary form) + べきではなかった (negative past)
- あんなことを言
( うべきではなかった - "I should not have said something like that."
- あんなことを言
Common uses
Giving strong advice
The speaker believes following the advice is important.
- 今日
( はもう休( むべきだ。 - You should rest today.
Expressing moral or social expectations
The speaker states what someone ought to do according to their values or society’s expectations.
- 子供
( は守( るべきだ。 - We should protect children.
Criticizing someone
Speakers use 〜べきだった when they believe someone made the wrong choice.
- あの時
( 説明( するべきだった。 - You should have explained it then.
Talking about oneself
A speaker can criticize their own actions.
- もっと早
( く気( 付( くべきだった。 - I should have realized sooner.
Further reading
- Things that should be a certain way (guidetojapanese.org)
- 〜べきだ|日本語能力試験 JLPT N 2 (edewakaru.com)
Related Grammar
Examples
Should be killed with 〜べき

Yui, Sacchan, and Kotoha are friends who’ve formed a group called Colors to protect their neighborhood. Yui is the group’s leader.
Yui hurries to the Colors clubhouse with news of a cat she saw. She draws it on paper, but Sacchan sees it as the sketch of a monster. Kotoha looks over the drawing and asks if they’re going to kill it.
- 結衣
( : - 「こ 殺
( すのはダメーッ」- “K-killing it is not okay!”
- 琴葉
( : - 「でも こんな化
( け物( ブッ殺( すべき」- “But a monster like this should be killed.”
- さっちゃん:
- 「そうだ じゃあ捕獲
( ならいいかリーダー」- “Right. Then is capturing it okay, Leader?”
- 結衣
( : - 「うんそれ!それにしよう!」
- “Yeah, that! Let's do that!”
Should have brought an umbrella with 〜べきだった
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On the way home from shopping, it starts raining.
- お母
( さん: - 「傘
( 持( つべきだったねー。」- “We should have brought an umbrella, huh?”
- お父
( さん: - 「そうだなー。」
- “You're right.”