ELECTROLESS PLATING APPARATUS AND ELECTROLESS PLATING METHOD

PROBLEM TO BE SOLVED: To provide an electroless plating apparatus and an electroless plating method, simply controllable of the composition of the plating liquid.SOLUTION: The electroless metal plating apparatus 1 includes a plating tank 2, metal melting tanks 30, 31 for replenishing metal ions in the plating liquid extracted from the plating tank 2, and an aeration tank 4 for generating aerated liquid by reducing the concentration of dissolved oxygen contained in the liquid supplied from the metal melting tanks 30, 31. The apparatus further includes a plating liquid conveying unit for conveying the plating liquid extracted from the plating tank 2 to the metal melting tanks 30, 31, a highly concentrated plating liquid conveying unit for conveying the highly concentrated plating liquid to the aeration tank 4 from the metal melting tanks 30, 31, an aerated liquid conveying unit for conveying the aerated liquid from the aeration tank 4 to the plating tank 2, and oxygen-enriched gas supply units 60, 61 for dissolving oxygen in the plating liquid. The metal melting tanks 30, 31 are capable of disposing and taking out metals included in the tanks, and adjusting the amount of dissolution of ions. The oxygen-enriched gas supply units 60, 61 are added to the metal melting tanks 30, 31, or the plating liquid conveying unit.