PURPOSE: To enhance the use life of a chemical plating bath and to attain to enhance the quality of a plated product, by adjusting the pH of the chemical plating bath of which the copper ion is consumed to a specific value while bringing the pH controlled plating bath into contact with the copper anode of an anode chamber to dissolve copper.

CONSTITUTION: The chemical plating bath of a chemical plating tank 4 is sent to a copper ion replenishing tank 3 and, when the pH of the plating bath reaches 11.5 or more, the plating bath is sent to an ion exchange tower 1 where an alkali component is removed by an H type cation exchange resin 2 to adjust the pH of the plating bath to 3W11. This pH controlled plating bath is sent to the anode chamber 6 of a diaphragm electritic cell 5. The anode 10 of the anode chamber 6 is constituted of a high purity electrolytic copper plate and a DC current is supplied to the electrolytic cell 5 to dissolve the copper plate of the anode 10 in the plating bath passing the anode chamber 6. The plating bath enhanced in a copper ion concn. is sent to the copper ion replenishing tank 3 and further sent to the chemical copper plating tank 4 through a recirculation tank 8 and a filter 21.