The present invention is to provide a substrate holder which can effect a more complete sealing with a sealing member and makes it possible to take a substrate out of the substrate holder easily and securely, and also a plating apparatus provided with the substrate holder. The substrate holder includes: a fixed holding member and a movable holding member for holding a substrate therebetween; a sealing member mounted to the fixed holding member or the movable holding member; and a suction pad for attracting a back surface of the substrate held between the fixed holding member and the movable holding member.