Abstract: A method for codepositing a water-insoluble material with a metal from a plating solution having the metal ion dissolved and the water-insoluble material suspended therein, characterized by pumping at least one third per minute of the volume of the plating solution by means of a pump without entraining air bubbles, and injecting the thus pumped volume downward into the bath through a plurality of holes in the lower side of a sparger pipe connected to said pump and located at a lower level in a plating tank, thereby circulating and fluidizing the plating solution in which codeposition is being carried out.