An insulated electric wire comprising a conductor and an insulating layer covering the conductor, wherein the insulating layer comprises a fluorinated copolymer (A) having units based on tetrafluoroethylene and units based on a perfluoroalkyl vinyl ether, the content of the units based on a perfluoroalkyl vinyl ether is from 0.1 to 1.9 mol % to the total units in the fluorinated copolymer (A); MRF of the fluorinated copolymer (A) as measured by the method in accordance with ASTM D-3307 is at least 0.1 and less than 15; the melting point of the fluorinated copolymer (A) is at least 260° C.; and the ratio of the thickness Di of the insulating layer to the diameter Dc of the conductor (Di/Dc) is less than 0.5.