An aromaheterocyclic derivative represented by the formula: wherein Z is a group represented by the following formula: wherein Ar1 is a phenyl group or a phenyl group substituted with a halogen atom or an alkyl group of 1 to 5 carbon atoms, R2 is an alkyl group of 1 to 5 carbon atoms, Y is a hydrogen atom, a mercapto group, an alkylthio group of 1 to 5 carbon atoms, an amino group or an amino group substituted with one or two alkyl groups having 1 to 5 carbon atoms, Ar2 is a phenyl group of one or two substituents selected from the group consisting of a halogen atom, an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, a hydroxyl group and a trifluoromethyl group, or a phenyl group, B1-B2 is CH—CO or C═C(R1) (wherein R1 is a hydrogen atom or an alkyl group of 1 to 5 carbon atoms), and n is an integer of 1 to 4, or a pharmaceutically acceptable salt thereof, which is a dopamine D4 receptor antagonist compound having an antipsychotic action without causing extrapyramidal diseases.