PURPOSE: To increase the yield of production and to improve reliability by forming a plating film having a uniform film thickness while preventing the adhesion of the bubbles generate at the time of applying an electroless plating on a semiconductor substrate to the plating film forming region of the semiconductor substrate.

CONSTITUTION: An electroless plating liquid 2 is stored in a hermetically closed plating cell 1 and a space 10 above the plating liquid 2 is connected via a discharge port 11 to a vacuum pump 5 and is held in a reduced pressure state. A reduction reaction arises and the plating film is formed in the plating film forming region if the surface of the barrier metal in the plating film forming region of the semiconductor substrate 3 mounted to a jig 4 comes into contact with the electroless plating liquid 2. The bubbles of the hydrogen generated by the reduction reaction at this time are easily desorbed by an air pressure difference.