The invention provides a rubber dispersed copolymer resin having excellent heat resistance, impact strength and moldability and composed of (1) a dispersed phase formed of a rubbery polymer and copolymerized styrene-type, acrylonitrile-type and maleimide-type monomers, said rubbery polymer specifically controlled occluding the copolymer of monomers, being grafted with the copolymer and/or forming a multicomponent gel together with copolymers, and (2) a continuous phase formed at least of a specifically controlled copolymer of the styrenetype, acrylonitrile-type and maleimide-type monomers. The resin is useful as a molding material for electric appliances, electronic equipment and cars.