A process is provided for roughening both sides of a copper plate by forming protrusions with fine bump shapes on both sides of the copper plate in an electroplating solution for plating copper while reducing deterioration of the electroplating solution. Opposed pairs of negative electrodes (3c) and positive electrodes (3a) are provided in an electroplating copper solution (2), and a copper plate (4) is arranged between the pair of negative electrodes (3c). An anodic treatment for generating copper fine particles on both surfaces of the copper plate (4) is carried out by performing an electrolytic process for three to ten minutes with the copper plate (4) as a positive electrode between the negative electrodes (3c). Then a cathodic treatment is carried out by moving the copper plate (4) between positive electrodes (3a) and performing an electroplating of copper for three to ten minutes with the copper plate (4) as a negative electrode for fixing the copper fine particles onto the surfaces of the copper plate (4). The cycle of anodic and cathodic treatment may be performed more than one time.