PURPOSE: To efficiently recover an electroless copper plating soln. by placing a chamber between a plating soln. regenerating chamber and an anode chamber and keeping a soln. in the placed chamber alkaline so as to prevent deterioration in the function of an anion exchange membrane by the deposition of a copper ion chelating agent.

CONSTITUTION: An aqueous NaOH soln. 11, 14 is poured into a cathode chamber 30 and a second intermediate chamber 40b and an aqueous H2SO4 soln. 12 is poured into an anode chamber 50. An exhausted electroless copper plating soln. 13 is then poured into a first intermediate chamber 40a and DC voltage is applied between the cathode 1 and anode 2 from a DC power source E to regenerate the plating soln. 13. The NaOH soln. 11 in the cathode chamber 30 and the NaOH soln. 14 in the second intermediate chamber 40b are circulated with pumps P1, P2 during dialysis.