Lesson 14 – How To Express Should Using べき・はずだ

Lesson 14 – How To Express Should Using べき・はずだ

During this lesson, you will be taught how to express the feeling of “should” or “ought to.” Since Japanese is a suggestive language this grammar point will prove to be especially useful in your Japanese learning journey.


There are two ways to express should in the Japanese language, and while the two of these grammar points are extremely similar there is still a distinction.

  1. べきだ

Think of べきだ as a casual way to express “should.” It is more casual because rather than expressing the listener’s judgment, it expresses the speaker’s judgment. You should not use べきだ when suggesting what someone else “must do.” It can be used as a soft suggestion for what they can do. Overall べきだ is a balance between formal statement and slack suggestions.


べき follows verbs in their plain dictionary form. It is always accompanied by the ender だ。It can be conjugated into present positive or negative depending on the situation.

Verb Dictionary Form + べきだ

Verb Dictionary Form + べきじゃない

Verb Dictionary Form + べきじゃなかった

Irregular Verb する(す) + べき・べきじゃなかった・べきじゃない




Since I have an exam I should eat something.



I should wash my hair.



We should see that new movie together.



I should take my medicine since I am sick.



You should not have said those things.



You were supposed to do your homework by yourself.



You should not just marry anybody!


  1. はずだ

If はず were to be compared to an English meaning, the closest term used to describe it would be “assumption.” Unlike べきだ、はずだ is used when the person has enough knowledge and experience about the noun being changed. It is more of a ‘predictive’ grammar form when matched up with べきだ。


はずだ is actually a noun itself, but it is never used alone. It can be used by adding it the end of a sentence after the conjugated verb or adjective.

Noun + はずだ

Verb + はずだ

~はずがない (Negative Form)



This book was not so hard to read. (Having experienced the book)


He should know that (judging on what I know he knows)


My mom should be here soon (judging on the information that I know already).


This grammar point is simple and works very well when in suggestive situations. But, always be careful when using べきだ as it should not be used for speaking to someone who is higher in status than you. Let us try an exercise to test your knowledge of べき・はず





What should you do in the following scenarios?

Use your imagination, but stick to the script ?

Answer In Japanese.


You are sick, and your doctor gives you medicine…

Your friend has no money…what should you do?

You want to buy a car in your favorite color. (Your color is red)

You need to wash your hair because you have a party to go to tomorrow.



Answer Key (Answers may vary)







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