Provided is a compound having an excellent Pim inhibition activity and useful as a medicinal agent. A thiazolidine derivative represented by general formula (1) (wherein X represents O, S or NH； R3 represents a hydrogen atom or an alkyl group； at least one of the dotted lines is a double bond； Z1, Z2 and Z6 independently represent C, CH or N； Z3, Z4, Z5, Z7 and Z8 independently represent C, CH, N, NH, O or S； Y represents a bivalent hydrocarbon group which has at least one C6-14 aromatic hydrocarbon group and may have a substituent, a bivalent aromatic heterocyclic group which may have a substituent, or a bivalent C2-12 aliphatic hydrocarbon group； Am represents an amino group, a mono-substituted amino group, a di-substituted amino group, or a nitrogenated saturated heterocyclic group which may have a substituent； and R1 and R2 independently represent a hydrogen atom, a halogen atom, an alkoxy group, a halogenoalkoxy group, or the like) or a salt thereof.
