Abstract: A method of producing a flexible single-sided polyimide copper-clad laminate having excellent flex properties. The method comprises: (A) forming a polyamic acid coating by applying a polyamic acid to the surface of a copper foil starting material, (B) forming a laminate by bonding a polyimide film to the polyamic acid coating, and (C) heat treating the laminate, wherein the copper foil starting material is a material for which, if the copper foil starting material is subjected to a heat treatment for 30 minutes at 200° C. in a non-oxidizing atmosphere and the intensity of the (200) plane determined by X-ray diffraction following this heat treatment is termed I, and if the intensity of the (200) plane determined by X-ray diffraction of a copper powder that has not been subjected to heat treatment is termed I0, I and I0 satisfy a relationship represented by a formula (I) shown below: I/I0>20 ??(I).