An insulated wire containing a thermoplastic resin layer (A) as a covering layer directly or indirectly on a rectangular conductor, in which the insulated wire has at least one protruding part which is continuous in a longitudinal direction of said insulated wire, on a surface of a portion of the thermoplastic resin layer (A), which portion corresponds to at least one side of a cross-section of the insulated wire, said protruding part and a flat part of the surface having the protruding part forms a curved portion with a radius of curvature of 0.01 to 0.75 mm in the cross-section of the insulated wire, and a lateral face of the protruding part has a slope of less than 90° to the flat part of the surface having the protruding part in the cross-section of the insulated wire, a coil produced by processing the insulated wire by winding, and an electric/electronic equipment comprising the coil.