Provided are: a novel compound having an excellent Aurora A selective inhibitory activity and useful as an anti cancer agent that can be administered orally； a novel anti tumor effect enhancer for a microtube agonist comprising a taxane type anti cancer agent； and a combination therapy. A piperidine compound represented by general formula (I) (wherein R represents a carboxyl group C(=O)NRR or an oxadiazolyl group which may have a C C alkyl group or a trifluoromethyl group as a substituent； R represents a halogen atom or a C C alkoxy group； R represents a phenyl group which may have 1 to 3 groups independently selected from a halogen atom a C C alkyl group a C C alkoxy group and a trifluoromethyl group as a substituent or substituents； R represents a hydrogen atom or a C C alkyl group； and R and R may be the same as or different from each other and independently represent a hydrogen atom a C C alkyl group or a C C cycloalkyl group or R R and a nitrogen atom to which R and R are bound may together form a 3 to 6 membered nitrogenated saturated heterocyclic group) or a salt thereof.
