A flame-retardant resin composition comprises a base resin (e.g., a polyester-series resin), a flame retardant (A) comprising a salt of an amino group-containing triazine compound with a sulfuric acid and/or a sulfonic acid, a flame-retardant auxiliary (B). The flame-retardant auxiliary (B) includes an aromatic resin, acyclic urea-series compound or a derivative thereof [e.g., acetyleneurea, uric acid, a salt of melamine or a condensate thereof (e.g., melam, melem, and melon) with cyanuric acid], an amino group-containing triazine compound (e.g., melamine or a condensate thereof), and/or an inorganic metal-series compound (e.g., a metal salt of an oxygen acid having no sulfur atom, a metal oxide, a metal hydroxide, and a metal sulfide). The present invention provides a flame-retardant resin composition to which flame retardancy is imparted without using a halogen-series flame retardant and an organic phosphorus-series flame retardant.