A copper foil for a printed wiring board, the copper foil being characterized by having, on at least one surface thereof, a roughed layer of the copper foil in which an average diameter at a particle root (D1) corresponding to a distance of 10% of a particle length from the root, is 0.2 μm to 1.0 μm, and a ratio of the particle length (L1) to the average diameter at the particle root (D1) is 15 or less when L1/D1. A copper foil for a printed wiring board, wherein a sum of area covered by holes on an uneven and roughened surface of a resin is 20% or more at a surface of the resin formed by laminating the resin and a copper foil for a printed wiring having a roughened layer and then removing the copper layer by etching. An object of the present invention is to develop a copper foil for a semiconductor package board in which the aforementioned phenomenon of circuit erosion is avoided without deteriorating other properties of the copper foil. In particular, an object of the present invention is to provide a copper foil for a printed wiring board and a producing method thereof, wherein a roughened layer of the copper foil can be improved to enhance the adhesiveness between the copper foil and a resin.