A quinazoline derivative represented by the formula (I) or a salt thereof, whichhas a PDE9-inhibiting activity and is useful as a therapeutic agent for dysuriaor the like. (I) wherein R represents a phenyl or aromatic heterocyclicgroup which may be substituted by 1 to 3 substituents selected from a halogen atom,a C alkyl group, a C haloalkyl group having 1 to 6 halogenatoms and a C alkoxy group； and n represents an integer ranging from1 to 3.
