A quinoxalinone derivative of the formula (I): or a pharmaceutically acceptable salt or ester thereof, wherein; X is NH, S or the like; Y is O or the like; the partial structure is, for example, the formula: B1, B2, . . . , Bn−1 and Bn, (in which n is 4, 5 or 6) are each independently CH, N or the like; B′1, B′2, . . . , B′n−1 and B′n (in which n is 4, 5 or 6) are each independently hydrogen or the like; and R is hydrogen, lower alkyl or the like.