A compound represented by the following formula or a pharmaceutically acceptable salt thereof wherein n represents 0 to 2; A represents a C 6-10 arylene group or a C 3-5 heteroarylene group; G represents a single bond, an oxygen atom or -CH 2 -; E represents a C 3-5 nitrogen-containing non-aromatic heterocycle; R 1 represents a cyano group, a mono-C 1-6 alkylamino group, a di-C 1-6 alkylamino group, a C 2-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms or one hydroxyl group, a C 1-6 alkoxy C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, or a C 1-6 alkoxy C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms; R 2 represents a hydrogen atom, a halogen atom, a hydroxyl group, a C 2-6 acyl group optionally substituted by one substituent selected from a group S described below, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a hydroxy C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, or a C 3-5 nitrogen-containing non-aromatic heterocyclic group; R 3 represents a hydrogen atom, an oxo group, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, or a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms; R 4 represents a C 1-6 alkyl group, with the proviso that when E represents an azetidine ring and R 2 or R 3 is present on a nitrogen atom on the azetidine ring, the R 2 or R 3 does not represent a hydrogen atom; and the group S represents a group consisting of a hydroxyl group, a mono-C 1-6 alkylamino group, a di-C 1-6 alkylamino group, a C 1-6 alkoxy group and a C 3-5 nitrogen-containing non-aromatic heterocyclic group. n represents 0 to 2; A represents a C 6-10 arylene group or a C 3-5 heteroarylene group; G represents a single bond, an oxygen atom or -CH 2 -; E represents a C 3-5 nitrogen-containing non-aromatic heterocycle; R 1 represents a cyano group, a mono-C 1-6 alkylamino group, a di-C 1-6 alkylamino group, a C 2-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms or one hydroxyl group, a C 1-6 alkoxy C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, or a C 1-6 alkoxy C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms; R 2 represents a hydrogen atom, a halogen atom, a hydroxyl group, a C 2-6 acyl group optionally substituted by one substituent selected from a group S described below, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, a hydroxy C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, or a C 3-5 nitrogen-containing non-aromatic heterocyclic group; R 3 represents a hydrogen atom, an oxo group, a C 1-6 alkyl group optionally substituted by 1 to 3 halogen atoms, or a C 1-6 alkoxy group optionally substituted by 1 to 3 halogen atoms; R 4 represents a C 1-6 alkyl group, with the proviso that when E represents an azetidine ring and R 2 or R 3 is present on a nitrogen atom on the azetidine ring, the R 2 or R 3 does not represent a hydrogen atom; and the group S represents a group consisting of a hydroxyl group, a mono-C 1-6 alkylamino group, a di-C 1-6 alkylamino group, a C 1-6 alkoxy group and a C 3-5 nitrogen-containing non-aromatic heterocyclic group.