A method for electrolytic treatment comprising forming electrochemically a rough surface on a material to be treated by supplying alternating current between the material to be treated and electrodes in an electrolytic solution containing metal ions, wherein when y[m/min.] indicates a travelling speed of the material, f[Hz] indicates line frequency and x[cm] indicates a distance between leading ends of the electrodes, an electrolytic roughening treatment is conducted by selecting x, y and f so as to satisfy the following formula; ##EQU1## (in the formula, g(a)=a-[a], here [a] indicates a maximum integer which does not exceed a.)