The purpose of the present invention is to provide an a, ß-unsaturated amide compound or a pharmaceutically acceptable salt thereof or the like, which has anti-cancer activity or the like. An a, ß-unsaturated amide compound represented by formula (I) and a pharmaceutically acceptable salt thereof or the like have anti-cancer activity or the like. (In the formula, A represents an optionally substituted heterocyclic diyl group； R1 represents a hydrogen atom or an optionally substituted lower alkyl group； R2 represents an optionally substituted aryl group, an optionally substituted cycloalkyl group, an optionally substituted aliphatic heterocyclic group or an optionally substituted aromatic heterocyclic group； X represents -O-, -S-, -SO2-, -NRX1- (wherein RX1 represents a hydrogen atom or a lower alkyl group), -CHRX2- (wherein RX2 represents a hydrogen atom or a hydroxy group), -CH=CH-, -CO- or -NH-CO-； and n1 and n2 may be the same or different, and each represents 0 or 1.)
