An object of the present invention is to provide a resin composition improved in film formability and/or mechanical property, particularly tensile elastic modulus or tearing strength, of the film. The present invention provides a resin composition including at least (A) an aliphatic polyester-based resin and (C) a starch, the aliphatic polyester-based resin (A) forming a matrix phase and the starch (C) forming a dispersed phase, wherein the average particle diameter of the dispersed phase is 1 μm or less.