To obtain a rubber-modified styrenic resin composition having a good balance between impact resistance and moldability, and to obtain a rubber- modified styrenic resin composition having a good balance between impact resistance and flame retardancy.

This rubber-modified styrenic resin composition comprises 100 pts.wt. of a rubber-modified styrenic resin, 0.005-0.5 pts.wt. of a fluororesin having a mol.wt. of 500,000-10,000,000 and a melting point of ≥260°C, and 0.1-10 pts.wt. of titanium dioxide. The rubber-modified styrenic resin preferably has a weight-average mol.wt. of 100,000-250,000.