A resin composition for molding, added with a nucleating agent suitable for promoting crystallization of a polyester capable of having a crystal structure, and in particular of a biodegradable polyester, and a molded product containing, the resin composition for molding thus improved in the crystallinity has either a cyclic compound expressed by general formula (I): (where each of A1, A2, A4 and A5 commonly or independently expresses —CO— or —NH—, each of A3 and A6 commonly or independently expresses hydrogen, halogen, optionally-substituted aliphatic group or optionally-substituted aromatic group) and having both of —CO— and —NH— in the molecule, or a mixture of (i) a cyclic compound having —CO— but no NH in the molecule and (ii) a cyclic compound having no —CO— but NH in the molecule, together with the polyester capable of having a crystal structure.