The present invention is to provide a piperidine compound represented by the formula [I]: wherein Ring A is an optionally substituted benzene ring, Ring B is an optionally substituted benzene ring, R1 is hydrogen atom or a substituent for amino group, R2 is hydrogen atom, an optionally substituted hydroxyl group, an optionally substituted amino group, an optionally substituted alkyl group, a substituted carbonyl group or a halogen atom, Z is oxygen atom or —N(R3)—, R3 is hydrogen atom or an optionally substituted alkyl group, R4a and R4b may be the same or different, and each is hydrogen atom or an optionally substituted alkyl group, or may be bonded to each other at the both ends to form an alkylene group, or a pharmaceutically acceptable salt thereof, which has an excellent tachykinin receptor antagonistic action.