The present invention provides a polycarbonate-based resin composition, including: a polycarbonate-based resin (S) containing a polycarbonate-polyorganosiloxane copolymer (A), which contains a polycarbonate block (A-1) formed of a specific repeating unit and a polyorganosiloxane block (A-2) containing a specific repeating unit; and a copolymer (B) including a constituent unit (b-1) having a specific structure, a constituent unit (b-2) having a specific structure, and a constituent unit (b-3) having a specific structure.