The invention discloses quinazoline derivatives or salts thereof,which possess PDE9-inhibiting activity and are useful as treatingagents of dysuria and the like, the derivatives being represented bythe formula (I)(see formula I)in the formula, R1 stands for phenyl or aromaticheterocyclic group which are optionally substituted with 1 - 3substituents selected from halogen, C1-6 alkyl, C1-6 haloalkylcontaining 1 - 6 halogen atoms and C1-6 alkoxy； and n is aninteger of 1 - 3.
