An object of the invention is to provide a resin composition which is particularly excellent in impact resistance, tensile elongation characteristics, heat resistance, surface properties, moldability and the like accompanied by less time dependent alteration of these properties and which is produced by mixing a certain plasticizer with a biodegradable polymer of plant origin, and to provide a molded product of the composition. The present invention can provide a resin composition comprising a biodegradable 3-hydroxyalkanoate copolymer (A) and a plasticizer (B), wherein: the biodegradable 3-hydroxyalkanoate copolymer (A) has a recurring unit represented by the structure formula (1): [—CHR—CH2—CO—O—] (wherein, R represents an alkyl group represented by CnH2n+1; and n is an integer of 1 to 15); the plasticizer (B) is based upon a polyglycerol acetic acid ester having an acetylation degree of no less than 50% ester.