The main purpose of the invention is to provide a novel aromatic heterocyclic derivative or a pharmaceutically acceptable salt thereof. Examples of the invention include aromatic heterocyclic derivatives represented by general formula [1] and pharmaceutically acceptable salts thereof. In formula [1]: R1 represents phenyl optionally substituted with one or two groups selected from the group consisting of halogens, as well as alkyls and alkoxys optionally substituted by halogens; R2 represents hydrogen, an alkyl, cycloalkyl, or alkoxy optionally substituted by a halogen, or a heteroaryl optionally substituted by an alkyl; X represents CR3, and Y represents N or CR4, or X represents N, and Y represents CR4; and Z represents CR5 or N.