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, n 1A represents 0 or 1； n 2A and n 3A may be the same or different, and each represents 1 or 2； R 0A represents optionally substituted aryl or the like； R 2A represents a hydrogen atom or the like； R 3A represents an optionally substituted aromatic heterocyclic group or the like； X 1A , X 2A , X 3A and X 4A each represent CH or the like； Y 1A represents CH 2 or the like； Y 2A represents N or the like； and L A represents CH 2 or the like) .
