To provide a foamed insulated wire, where transmission characteristics are stabilized by dissolving unevenness on the outer surface of an insulating layer and dispersion of outer diameters when the insulating layer is formed by winding a porous polyethylene tape.

This foamed insulated wire contains a compound insulating layer 4 that comprises an inner insulating layer 2 formed by winding a porous polyethylene tape having weight-average molecular weight of 5 millions or more and a porosity of 80% or more around a periphery of a conductor 1 and an outer insulating layer 3 having a thickness of 0.20 mm or less and a variation of outer diameters of ±0.02 mm or less.