Self-bonding insulated wire and wire for coil

The present invention addresses the problem of providing a self-bonding insulated wire that makes it easy to fasten wires together and that is unlikely to generate dust. A self-bonding insulated wire according to one embodiment of the present invention is provided with a linear metal conductor, an insulating layer that is layered on the outer circumferential side of the metal conductor, an expansion layer that is layered on the outer circumferential side of the insulating layer and that expands as a result of being heated, and a thermal bonding layer that is layered on the outer circumferential side of the expansion layer. The expansion layer may comprise: a matrix having a synthetic resin as a main component; and thermally expandable microcapsules or a chemical foaming agent that are dispersed in the matrix. The average thickness expansion rate of the expansion layer after heating is preferably 1.1 to 5 times. The porosity of the expansion layer after heating is preferably 10 to 80%. The average thickness of the thermal bonding layer is preferably 5 to 200 [mu]m.