Disclosed is an impact-resistant methacrylic resin composition which comprises a graft copolymer [II] obtained by polymerizing 10 to 900 wt. parts of a monomer or monomeric mixture (B) comprising 80 to 100 wt. % methyl methacrylate and 20 to 0 wt. % of at least one vinyl or vinylidene monomer copolymerizable therewith in the presence of 100 wt. parts of an acrylic elastomer [I] obtained by polymerizing monomeric mixture (A) comprising 9.9 to 29.9 wt. % of styrene and/or its derivative, 70 to 90 wt. % of at least one alkyl (C2-8) acrylate, 0.1 to 5 wt. % of at least one monomer represented by the formula: ##STR1## and 0 to 5 wt. % of a crosslinkable copolymerizable monomer having at least 2 carbon-to-carbon double bonds. This graft copolymer [II] may be used in combination with a methacrylic resin [III] obtained by polymerizing a monomer or monomeric mixture (C) comprising 80 to 100 wt. % methyl methacrylate and 20 to 0 wt. % of at least one copolymerizable vinyl or vinylidene monomer. The impact-resistant resin composition has excellent transparency and weatherability and a good surface gloss.