An insulated electric wire includes a conductor comprising twisted elemental wires and an insulation covering. The insulated electric wire includes an exposed portion in which the insulation covering is removed from the outer surface of the conductor, and a covered portion in which the insulation covering covers the outer surface of the conductor. The exposed portion and the covered portion are adjacent with each other along a longitudinal axis of the insulated electric wire. A density of the conductive material per unit length is higher in the exposed portion than in the covered portion. The elemental wires are twisted in both the exposed portion and the covered portion including an area that is positioned away from the exposed portion by at least a distance corresponding to a length of the exposed portion. Gaps between the elemental wires of the exposed portion are filled with a sealant.