Resin composition and molded article thereof

A method of reducing a crystallinity of a polyolefin-based resin, comprising:

• adding a nucleating agent and a fatty acid metal salt to a polyolefin-based resin such that the nucleating agent is contained in an amount of 0.005 to 0.08 parts by mass and the fatty acid metal salt is contained in an amount of 0.001 to 0.05 parts by mass, with respect to 100 parts by mass of the polyolefin-based resin,
• wherein the nucleating agent comprises an acetal compound represented by the following Formula (2):
• wherein, R1 represents an alkyl group having 1 to 4 carbon atoms;
• R2, R3, R4 and R5 each independently represent a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, or R2 and R3 or R4 and R5 are linked together to represent an alkylene group having 3 to 6 carbon atoms or an alkylenedioxy group having 1 to 4 carbon atoms;
• and X represents a single bond, a —CH(OH)— group, or a —CH(OH)CH(OH)— group.