This study aims to reveal how much time and effort Japanese language learners should devote to learning idiomatic phrases, and which idiomatic phrases should be learned preferentially. We measured the frequency of use of idiomatic phrases in numerous of sentences appearing in articles from the newspapers Asahi, Mainichi, and Yomiuri. Idiomatic phrases were extracted from "Nihongo no Kan'youhyougen Jiten" (2014), written by Yoshiyuki Morita, and notational variants of these phrases were added manually. The results showed that less than one idiomatic phrase occurred in every 1,000 characters of the newspaper articles. The 30 idiomatic phrases with the highest frequency were revealed in this study.