To support the real-time understanding of spoken monologue such as lectures and commentaries, the development of a captioning system is required. In monologues, since a sentence tends to be long, each sentence is often displayed in multi lines on one screen, it is necessary to insert linefeeds into a text so that the text becomes easy to read. This paper proposes a technique for inserting linefeeds into a Japanese spoken monologue text as an elemental technique to generate the readable captions. .