A resin composition includes at least a cellulose ester resin, a non-reactive plasticizer that does not have a functional group reactable with the cellulose ester resin, and a polyolefin-containing polyfunctional elastomer that includes polyolefin obtained by polymerizing olefins having 2 to 4 carbon atoms as a main component and that has a plurality of functional groups reactable with the cellulose ester resin.