The purpose of this paper is to show the practical state of the idiom dictionary and the plan for a improvement. In order to show the practical state of the idiom dictionary, we examined the system of 「Idiom Dictionary」(Choi &ark. 1996) and discussed the significance. At this time the examination was carried out in three sides that are the entry. the explanation of meaning and the example sentence. The plan for a improvement was carried out in three sides too. So in this paper we tried to answer about three questions. How to select and arrange the entries? How to explain the meaning of idioms? How to select the example sentence?