Insulated electric wire

An insulated electric wire, comprising:

• a conductor;
• and
• an insulating layer disposed around an outer circumference of the conductor,
• wherein the insulating layer is formed from a fluorine-containing elastomer composition, and the fluorine-containing elastomer composition includes a base polymer (A) including 90% by mass or more and 98% by mass or less of a tetrafluoroethylene-propylene copolymer (a1), and 2% by mass or more and 10% by mass or less of an ethylene-ethyl acrylate copolymer (a2) (excluding an ethylene-ethyl acrylate-maleic anhydride ternary copolymer), and a flame retardant (B) including an antimony compound (b1) and a bromine-based flame retardant (b2), and including 1 part by mass or more and 9 parts by mass or less of the antimony compound (b1), and 0.3 parts by mass or more and 15 parts by mass or less of the bromine-based flame retardant (b2) per 100 parts by mass of the base polymer (A), and
• wherein the insulating layer has a heat resistance that when the insulating layer is heat-aged at 250 degrees C. for 4 days, a retention of tensile strength of the insulating layer is 80% or more, and a retention of enlongation of the insulating layer is 80% or more.