A fire-retardant resin composition, comprising: a thermoplastic resin component (A) of (a) a (hydrogenated) block copolymer mainly made of a vinyl aromatic compound and a conjugated diene compound, (b) a nonaromatic-series softener for rubber, (c) an ethylene/.alpha.-olefin copolymer, (d1) an ethylene copolymer with either/vinyl acetate (meth)acrylic acid or meth/acrylate, (e) a polypropylene resin, and (f) a modified polyethylene resin; and (g) an organic peroxide, (h) a (meth)acrylate-series and/or allyl-series crosslinking aid, and a metal hydrate (B), wherein a specific amount of the metal hydrate (B) is one pretreated with a silane coupling agents.