A resin composition has a first resin, a second resin incompatible with the first, and a modified elastomer having a reactive group capable of reacting with the first resin. The resin composition has a co-continuous phase structure including continuous phases A and B respectively formed of the first and second resins, dispersed domains a and b respectively distributed in the continuous phases A and B, and finely dispersed subdomains a′ and b′ respectively distributed in the dispersed domains a and b. The dispersed domain a includes a dispersed domain formed of at least one of the second resin and a first resin, modified elastomer reaction product, the dispersed domain b at least one of the first resin and the reaction product, and the finely dispersed subdomains a′ and b′ each independently at least one of the first resin, the second resin, the modified elastomer, and the reaction product.