のは～だ

The structure のは～だ is used to nominalize a clause with の and then highlight or identify a specific piece of information about it using は〜～だ. This creates what is sometimes called a cleft sentence – similar to English constructions like "It is … that …" or "What … is …".

Emphasizing specific information

By restructuring a sentence with のは～だ, you can draw attention to who, what, when, where, or why something happened.

Compare the neutral sentence わたくし私はまいあさ毎朝こうひいコーヒーをのむ飲む ("I drink coffee every morning") with the cleft version above – the cleft version specifically highlights coffee as the key piece of information.

Stating reasons

A very common use of のは～だ is to explain the reason for something. In this case, the predicate typically ends with からだ or ためだ.

Important notes

• The clause before のは must be in plain form (dictionary form, た-form, ない-form, etc.). Use な after な-adjectives and nouns (e.g. すき好きなのは, がくせい学生なのは).
• The polite version uses です instead of だ at the end:
  わたくし私がたのしみにしている楽しみにしているのはりょこう旅行です。

  What I'm looking forward to is the trip.
• Be careful not to confuse this with the explanatory のだきごう／んだ pattern. In のは～だ, の nominalizes the preceding clause and は marks it as the topic, whereas のだ adds explanation or emphasis to a whole statement.