The present invention provides a non-halogen resin composition, an insulated electrical wire formed of the non-halogen resin composition, and a wire harness including the insulated electrical wire. The non-halogen resin composition, comprising: (A) 100 parts by weight of a base resin, containing 50 to 75 weight percent of a polypropylene, 20 to 40 weight percent of a propylene-alpha olefin copolymer, and 5 to 10 weight percent of a low density polyethylene; (B) 50 to 100 parts by weight of a metal hydroxide; (C) 3 to 5 parts by weight of a phenolic anti-oxidant; and (D) 0.5 to 2 parts by weight of a hydrazine-containing metal capture agent. The non-halogen resin composition exhibits excellent mechanical properties such as abrasion resistance, flame retardant property, flexibility, and long-term heat resistance, even if it contains inorganic flame retardant therein.