The present invention provides a metastin derivative having excellent blood stability and exhibiting cancer metastasis inhibiting action or cancer growth inhibiting action. Specifically, the present invention the metastin derivative (I), which is represented by formula: [wherein, Z1, Z3, Z5 and Z7 represent H or a C1-3 alkyl group Z2, Z4, Z6 and Z8 represent H, O or S R1 represents (1) H, or (2) a C1-8 alkyl group optionally substituted with a substituent selected from the group consisting of a carbamoyl group, a hydroxyl group and a aromatic cyclic group R2 represents (1) H or (2) a cyclic or linear C1-10 alkyl group, or (3) a C1-10 alkyl group consisting of a cyclic alkyl group and a linear alkyl group R3 represents a C1-8 alkyl group having a basic group, an aralkyl group having a basic group, a C1-4 alkyl group having a non-aromatic cyclic hydrocarbon group of carbon atoms not greater than 7 having a basic group, or a C1-4 alkyl group having a non-aromatic heterocyclic group of carbon atoms not greater than 7 having a basic group R4 represents a C1-4 alkyl group, which may optionally be substituted with a substituent selected from the group consisting of a C6-12 aromatic hydrocarbon group, an aromatic heterocyclic group, a C8-14 aromatic fused-ring group, an aromatic fused heterocyclic group, a non-aromatic cyclic hydrocarbon group, and a non-aromatic heterocyclic group having carbon atoms not greater than 7 X represents a group shown by formula: -NHCH(Q1)YQ2C(=Z9)- (wherein, Q1 represents a C1-4 alkyl group, which may optionally be substituted with a substituent selected from the group consisting of an aromatic hydrocarbon group, an aromatic heterocyclic group, a C8-14 aromatic fused-ring group, an aromatic fused heterocyclic group, a non-aromatic cyclic hydrocarbon group having carbon atoms not greater than 7, and a non-aromatic heterocyclic group having carbon atoms not greater than 7 Q2 represents CH2, NH or O Y represents -CONH-, -CSNH-, -CH2NH-, -NHCO-, -C
