This insulated flat conductive wire includes: a flat conductive wire having an aspect ratio a/b of 12 or more, wherein the aspect ratio is a ratio of a length a of a long side of a rectangular cross-section to a length b of a short side thereof; and an insulating film which consists of a polyamide-imide resin or a polyimide resin and coats the flat conductive wire, wherein the insulating film has a film thickness t1 of 10 μm or more at a center portion of the long side of the rectangular cross-section, and the insulating film has a film thickness ratio t1/t2 of 0.80 to 1.35, and wherein the film thickness ratio t1/t2 is a ratio of the film thickness t1 at the center portion of the long side to a film thickness t2 at an edge portion of the long side of the rectangular cross-section.