The present invention relates to a flame-retardant resin composition comprising: (A) 60 to 98 wt % of a thermoplastic resin comprising a rubber-reinforced resin; and (B) 40 to 2 wt % of a halogen type flame-retardant which comprises a mixture of compounds, the mixture comprising 5 to 60 mol % of a compound (B-1) having epoxy groups at both terminals of the molecular chain, 15 to 70 mol % of a compound (B-2) having epoxy group at one terminal alone and 5 to 80 mol % of a compound (B-3) having no epoxy group at both terminals.