The purpose of the present invention is to provide: a therapeutic agent or a recurrence preventive agent for serotonergic system- or dopaminergic system-related diseases, in particular, mental dysfunction symptoms and other non-motor symptoms of Parkinson's disease； and a method for treating the aforesaid symptoms or preventing the recurrence of the same. A compound represented by formula (1) [wherein each symbol is as defined in the description] or a pharmaceutically acceptable salt thereof can exhibit an effect of treating serotonergic system- or dopaminergic system-related diseases, in particular, mental dysfunction symptoms and other non-motor symptoms of Parkinson's disease and/or an effect of preventing the recurrence of the same.
