Should be with 〜べきだ

Grammar: Necessity » 〜べき

Usage Notes

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

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1. Verb (dictionary form) ＋ べきだ
   • 約束(やくそく)は守(まも)るべきだ
   • "One should keep promises."
2. 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.
3. Verb (dictionary form) ＋ べきではない (negative)
   • 嘘(うそ)をつくべきではない
   • "You shouldn't tell lies."
4. Verb (dictionary form) ＋ べきじゃない (casual negative)
   • そんなこと言(い)うべきじゃないよ
   • "You shouldn't say something like that."
5. Verb (dictionary form) ＋ べきだった (past)
   • もっと早(はや)く謝(あやま)るべきだった
   • "I should have apologized sooner."
   • Note: The past form can carry a sense of regret.
6. Verb (dictionary form) ＋ べきではなかった (negative past)
   • あんなことを言(い)うべきではなかった
   • "I should not have said something like that."

Giving Strong Advice

The speaker believes following the advice is important.

• 今日(きょう)はもう休(やす)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(こども)は守(まも)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(とき)説明(せつめい)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(はや)く気(き)付(づ)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

• 〜たほうがいい
  • Gives mild advice.
• 〜なければならない
  • Indicates necessity or obligation.
• 〜なくてはいけない
  • Similar to 〜なければならない, but less formal.
• 〜てもいい
  • Gives permission.

Examples

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Should be killed with 〜べき

Grammar Explanation: Should be with 〜べきだ

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(ゆい):

「こ　殺(ころ)すのはダメーッ」

“K-killing it is not okay!”

琴葉(ことは):

「でも　こんな化(ば)け物(もの)ブッ殺(ころ)すべき」

“But a monster like this should be killed.”

さっちゃん:

「そうだ　じゃあ捕獲(ほかく)ならいいかリーダー」

“Right. Then is capturing it okay, Leader?”

結衣(ゆい):

「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

Grammar Explanation: Should be with 〜べきだ

On the way home from shopping, it starts raining.

お母(かあ)さん:

「傘(かさ)持(も)つべきだったねー。」

“We should have brought an umbrella, huh?”

お父(とう)さん:

「そうだなー。」

“You're right.”