To obtain a composition which gives a molding excellent in moldability and impact strength, having good surface appearance and hardly marred on the surface by incorporating a specific amount of a compound of a specific structure into a rubber-containing styrenic resin.

Into 95-99 pts.wt. of a rubber-containing styrenic resin (A) are incorporated 1-5 pts.wt. of a compound (B) of the formula. As the component A is employed a resin composed of a copolymer to form a dispersion phase comprising a robbery polymer which has grafted thereto a copolymer comprising an aromatic vinyl and a vinyl cyanide and containing copolymers of a wt. average particle size of 0.05-0.15 μm and those of a wt. average particle size of 0.3-0.5 μm in an amount of 50-70 wt.% and 30-50 wt.%, respectively and 10-40 wt.% of the rubbery polymer, and a copolymer to form a matrix phase comprising an aromatic vinyl and a vinyl cyanide. In the formula, R1 is alkyl; R2 and R3 are each H or methyl; R4 is alkyl or -C(0)R6; R5 is H, alkyl or -C(O)R7 (wherein R6 and R7 are each alkyl); and m and n are each 1-20.