A compound represented by formula (1) or a pharmaceutically acceptable salt thereof has an inhibitory effect in the fractalkine-CX3CR1 pathway: wherein R represents a C 1-6 alkyl group unsubstituted or having 1 to 3 substituents selected from Substituent Group A, a C 3-8 cycloalkyl group unsubstituted or having 1 to 3 substituents selected from Substituent Group A, or a C 3-8 cycloalkenyl group unsubstituted or having 1 to 3 substituents selected from Substituent Group A, X represents a C 1-6 alkyl group, Y and Z are the same or different from each other and each represents a halogen atom or a C 1-6 alkyl group unsubstituted or having 1 to 3 substituents selected from Substituent Group B, n represents 0 or 1, Substituent Group A consists of halogen atoms, and Substituent Group B consists of halogen atoms.
