Provided is a surface-treated copper foil which can impart a contour shape to a surface of a substrate after removing a copper foil, and which maintains fine wiring formation properties and achieves good adhesion of an electroless copper plating film. Further, there is provided a resin substrate having a contour of a surface which maintains fine wiring formation properties and achieves a good adhesion force of an electroless copper plating film. In the surface-treated copper foil of the present invention, a surface-treated layer is formed on the copper foil, and the surface roughness Sz of the surface of the surface-treated layer is 2 to 6 μm.