An insulated wire includes a conductor, and an insulation layer covering an outer periphery of the conductor. The insulation layer includes a halogen-free flame-retardant resin composition including a base polymer, not less than 1 part by mass and not more than 10 parts by mass of an amorphous silica and not less than 10 parts by mass and not more than 150 parts by mass of a halogen-free flame retardant relative to 100 parts by mass of the base polymer. The base polymer includes not less than 50 parts by mass and not more than 90 parts by mass of either an ethylene-vinyl acetate copolymer or an ethylene-butene copolymer and not less than 10 parts by mass and not more than 50 parts by mass of a low-density polyethylene.