The present invention provides a compound represented by formula (I), (in the formula, A 1 and A 2 each independently represents a carbon atom or a nitrogen atom; X 1 represents an unsubstituted or substituted C1-6 alkyl group or the like; n represents an integer of 0 to 4; R 1 represents an unsubstituted or substituted C1-6 alkylthio group or the like; B 1 and B 4 each independently represent a carbon atom, a nitrogen atom or the like; R 2 and R 3 each independently represent a hydrogen atom, a halogeno group or the like; Ar represents an unsubstituted or substituted C6-10 aryl group or the like) or a salt thereof, and a harful organism control agent including thereof.