A precursor of a molecular probe for imaging of pancreatic islets is provided. The precursor includes a polypeptide represented by any one of the following formulae (1) to (12), or a polypeptide having a homology with the foregoing polypeptide: *-DLSKQMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (1) *-LSKQMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (2) *-SKQMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (3) *-KQMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (4) *-DLSK* QMEEEAVRLFIEWLKNGGPSSGAPPPS-NH 2 (5) *-LSW QMEEEAVRLFIEWLKNGGPSSGAPPPS-NH 2 (6) *-SK* QMEEEAVRLFIEWLKNGGPSSGAPPPS-NH 2 (7) *-K* QMEEEAVRLFIEWLKNGGPSSGAPPPS-NH 2 (8) DLSK* QMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (9) LSK* QMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (10) SK* QMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (11) K* QMEEEAVRLFIEWLK* NGGPSSGAPPPS-NH 2 (12)
