Grammar Info
N3 Lesson 1: 9/23

べきではない
should not, must not , ought not to

する → すべきではない・するべきではない

Structure
Casual
Formal
Verb + べき + ではない
Verb + べき + じゃない
Verb + べき + ではありません
Verb + べき + じゃありません
Details
Register Standard
使用域 一般
可き
Information
As an extension of the 助動詞(じょどうし) (auxiliary verb) べき, that is partnered with verbs to convey ‘ought to do (A)’, べきではない (or べきじゃない) highlights the opposite, and means ‘ought not to (A)’, ‘should not (A)’, or ‘must not (A)’. Just like べき, it is quite strong, and implies that doing (A) would be considered improper/incorrect.
べきではない (or べきじゃない) will be paired with the plain (non-past) form of a verb.
  • 濡(ぬ)れている手(て)コンセント触(ふ)れるべきではない
    You must not touch the outlet with wet hands.
  • どんないう事(こと)聞(き)かなくても、子供(こども)手(て)あげるべきじゃない
    No matter how much a child doesn't listen to what you say, you ought not to raise your hand at them.
Caution
As with all other structures that use では, は may be omitted. However, as the presence of は strengthens the ない, the overall phrase will sound a little bit weaker without it.
  • 一人(ひとり)であの山(やま)行(い)くべきではない
    You must not go to that mountain alone.
  • 人(ひと)傷(きず)つけるような事(こと)言(い)うべきでない
    You ought not to say anything that could hurt a person's feelings.
Fun Fact
The combination of する and べき is a rare grammatical exception in Japanese, in which two forms are both considered equally correct. Due to this, either するべき, or すべき may be used.
  • テストの前(まえ)に徹夜(てつや)するべきではない
    You ought not to stay up all night before a test.
  • くだらないこと警察(けいさつ)電話(でんわ)すべきではない
    You must not call the cops for something trivial.
Slow Male
Hide All
Hide Japanese
Hide English
腐(くさ)っている食(た)べ物(もの)食(た)べるべきではない
You shouldn't eat food that is rotten.
Play  
禁煙(きんえん)場所(ばしょ)では、タバコを吸(す)うべきではない
You must not smoke in places that are non-smoking.
Play  
大(たい)したことない心配(しんぱい)するべきではない
It's not important. You shouldn't worry about it.
Play  
Books
Tae Kim's Japanese Grammar Guide
Page 309
[AIAIJ] An Integrated Approach to Intermediate Japanese
Page 55