The present invention relates to an insulated electric wire for an automobile containing a conductor and an insulating coating layer which coats the conductor, the insulating coating layer being formed of a non-crosslinkable resin composition containing 65 to 90 parts by weight of a polypropylene-based resin, 10 to 40 parts by weight of a metal hydroxide, 20 to 50 parts by weight of a bromine-based flame retardant, 5 to 30 parts by weight of antimony trioxide, and 2 to 15 parts by weight of a maleic acid-modified resin in the ratio and further containing at least one of 3 to 10 parts by weight of a polyethylene resin and 2 to 10 parts by weight of an ethylene-based copolymer.