A substrate holder capable of being used in both single-side plating and double-side plating is required. Disclosed is a substrate holder for holding a substrate to be plated. The substrate holder includes a first frame having a first opening for exposing one surface of the substrate and a second frame having a second opening for exposing the other surface of the substrate, and the substrate is sandwiched between the first frame and the second frame. The substrate holder further includes a dummy substrate which is detachably disposed between the first frame and the substrate and formed of a material that at least direct current does not substantially flow therein. At least a part of the dummy substrate is in contact with at least a part of the one surface of the substrate, and the dummy substrate protects the one surface of the substrate from a plating solution.