A polycarbonate resin composition with improved moisture resistance maintains outstanding physical properties even in high-temperature, high-humidity aging and comprises a polycarbonate resin composition containing (B) (B-1) 1 to 99 parts by weight of a copolymer having as its component parts (a) an aromatic vinyl monomer component, (b) a cyanide vinyl monomer component, and (c) a rubber-like polymer, and/or (B-2) a copolymer having as its component parts (a) an aromatic vinyl monomer component and (b) a cyanide vinyl monomer component, with respect to (A) 1 to 99 parts by weight of polycarbonate resin having a viscosity average molecular weight within a specified range, said copolymer containing an amount of various alkali metals of 1 ppm or less, and (C) 0 to 40 parts by weight of a phosphoric ester compound blended in with respect to a total of 100 parts by weight of the aforementioned components (A) and (B).