A resin composition includes a polycarbonate-based resin and a polyethylene terephthalate resin, and the resin composition has a resin phase-separated structure including a continuous phase containing the polycarbonate-based resin and a dispersed phase containing the polyethylene terephthalate resin, in which a number average diameter in a longitudinal direction of the dispersed phase is 1.5 μm or less, a number average diameter in a lateral direction of the dispersed phase is 0.8 μm or less, and an aspect ratio of the number average diameter in the longitudinal direction to the number average diameter in the lateral direction is 2.5 or less.