A pyrimidone derivative represented by formula (I) or a salt thereof, or a solvate thereof or a hydrate thereof: wherein: X represents two hydrogen atoms, a sulphur atom, an oxygen atom or a C 1-2 alkyl group and a hydrogen atom； Z represents a bond, an oxygen atom, a nitrogen atom substituted by a hydrogen atom or a C 1-3 alkyl group, a sulphur atom, a methylene group optionally substituted by one or two groups chosen from a C 1-6 alkyl group, a hydroxyl group, a C 1-6 alkoxy group, a C 1-2 perhalogenated alkyl group or an amino group； R1 represents a 2, 4 or 5-pyrimidine ring or a 4-pyridine ring, the ring being optionally substituted by a C 1-6 alkyl group, a C 1-6 alkoxy group or a halogen atom； R2 represents a benzene ring, a naphthalene ring or a benzyl group ； the rings being optionally substituted by 1 to 4 substituents selected from a C 1-6 alkyl group, C 3-7 cycloalkyl group, a C 3-7 cycloalkyl-C 1-6 alkyl group, a halogen atom, a C 1-2 perhalogenated alkyl group, a C 1-3 halogenated alkyl group, a hydroxyl group, an heteroaryl group optionally substituted by a C 1-6 alkyl group, C 3-7 cycloalkyl group, a C 3-7 cycloalkyl-C 1-6 alkyl group, C 1-6 alkoxy group optionally substituted by a C 3-5 cycloalkyl group, a C 1-2 perhalogenated alkoxy group, a C 1-6 alkylsulfonyl group, a nitro, a cyano, an amino, a C 1-6 monoalkylamino group or a C 2-12 dialkylamino group, an acetoxy group or an aminosulfonyl group； R3 represents a hydrogen atom, a C 1-6 alkyl group or a halogen atom； R4 represents a hydrogen atom or a C 1-6 alkyl group； R5 represents a hydrogen atom, a C 1-6 alkyl group； R6 represents a hydrogen atom, a C 1-6 alkyl group； R7 represents a hydrogen atom or a C 1-6 alkyl group； n represents 0 to 3 and m represents 0 in the form of a free base or of an addition salt with an acid.
