Disclosed are a fire retardant thermoplastic resin composition suitable for preparing an electric wire, etc. by enhancing extrudability of a resin composition without hindering fire retardancy of the resin composition, and an electric wire comprising the same. The fire retardant thermoplastic resin composition comprises a matrix resin that comprises 20 to 35% by weight of a poly arylene ether resin, 20 to 35% by weight of a vinyl aromatic resin and 5 to 20% by weight of an olefin-based resin comprising a rubber ingredient, 1 to 10% by weight of a room-temperature liquid-type fire retardant, and 8 to 20% by weight of an ancillary fire retardant, based on 100% by weight of a mixture of a poly arylene ether resin, a vinyl aromatic resin, an olefin-based resin, a room-temperature liquid-type fire retardant and an ancillary fire retardant.