For flexible printed circuit boards chip on film

There is provided a flexible printed wiring board including an insulating layer having a high optical transmittance, a high adhesion strength and a high migration resistance, and suitable for a chip on film (hereafter referred to as COF). In a flexible printed wiring board for COF, having an insulating layer on which a conductive layer of an electrodeposited copper foil is laminated, and an optical transmittance of 50% or more of the insulating layer in the etched region when a circuit is formed by etching said conductive layer, electrodeposited copper foil was made to have a rust-proofing layer of a nickel-zinc alloy on the adhering surface to be adhered to the insulating layer; the surface roughness (Rz) of the adhering surface was made to be 0.05 to 1.5 mum, and the specular gloss was made to be 250 or more when the incident angle is 60°.