PURPOSE: To reduce the fluctuation of the flow rate of an electroforming liquid and to facilitate the adjustment thereof by branching a part of the electroforming liquid flowing into electroforming tanks and joining it with the electroforming liquid flowing out of electroforming tanks via a piping having an flow rate regulating valve.

CONSTITUTION: The electroforming liquid carried from an electroforming liquid control tank 1 successively passes through filters 3-1, 3-2 by a pump 2 and then in branched and supplied to electroforming tanks 6-1, 6-2 through flow control valves 4-1, 4-2 and flowmeters 5-1, 5-2. The electroforming liquid flowing out thereof is circulated to the control tank 1 and the electroforming of a stamper for an optical disk, etc., is executed. In the electroforming device, a pipe 7 which branches a part of the electroforming liquid flowing into electroforming tanks 6-1, 6-2 and then joins it with the electroforming liquid flowing out of electroforming tanks 6-1, 6-2 is arranged and a flow control valve 4-3 and a flowmeter 5-3 are provided on the half-way of the pipe 7. In such a manner, the fluctuation of the flow rate of the electroforming liquid is reduced and can easily be regulated and the stamper, etc., having stable physical characteristics are obtained.