A Wnt signaling inhibitor which comprises, as an active ingredient, a fused-ring heterocyclic compound represented by the following formula (IA) or a pharmaceutically acceptable salt thereof, and the like are provided: (wherein, n1A represents 0 or 1; n2A and n3A may be the same or different, and each represents 1 or 2; ROA represents optionally substituted aryl or the like; R2A represents a hydrogen atom or the like; R3A represents an optionally substituted aromatic heterocyclic group or the like; X1A, X2A, X3A and X4A each represent CH or the like; Y1A represents CH2 or the like; Y2A represents N or the like; and LA represents CH2 or the like).