An object of the present invention is to provide a polyorganosiloxane-containing graft copolymer powder capable of providing a resin composition and a molded article which are excellent in balance between colorability and mechanical properties such as impact resistance. The polyorganosiloxane-containing graft copolymer powder according to the present invention is a graft copolymer powder obtained by graft-polymerizing a mixture (B) of a vinyl monomer (b1) having an epoxy group and another vinyl monomer (b2) to a rubber (A) containing a polyorganosiloxane, wherein the content of the polyorganosiloxane (A1) contained in the rubber (A) is 12 to 50% by mass, the mass average particle diameter of the polyorganosiloxane-containing graft copolymer powder is 300 to 2000 nm, and the epoxy equivalent of the polyorganosiloxane-containing graft copolymer powder is 2500 to 7800 g/eq.