A molecular probe for imaging of pancreatic islets is provided. The molecular probe includes a polypeptide represented by the following formula (1), or a polypeptide that has a homology with the foregoing polypeptide.(SEQ ID NO. 1) Z-HGEGTFTSDLSKQMEEEAVRLFIEWLKNGGPSSGAPPPSX-NH2 (1) Wherein “X” represents a lysine residue, an amino group of a side chain of the lysine residue being labeled with a group represented by the following chemical formula (I),wherein A represents an aromatic hydrocarbon group or an aromatic heterocyclic group R1 represents a substituent that contains 11C, 13N, 15O, 18F, 64Cu, 67Ga, 68Ga, 75Br, 76Br, 77Br, 99mTc, 111In, 123I, 124I, 125I, or 131I R2 represents either a hydrogen atom, or a substituent different from that represented by R1 and R3 represents any one of a bond, an alkylene group having 1 to 6 carbon atoms, and an oxyalkylene group having 1 to 6 carbon atoms.
