A method for holding a substrate on the substrate holder is provided, and in this method, the substrate holder includes a front frame, a rear frame, a clamper for clamping the front frame and the rear frame; and seals configured to come into contact with the substrate and one of the front frame and the rear frame when the front frame and the rear frame are clamped. The method includes pressing at least one of the front frame and the rear frame toward another one to press the seals against the substrate, and compressing the seals; and clamping the front frame and the rear frame by the clamper in a state that the seals are compressed. During the seals being compressed, a place where a force is applied to at least one of the front frame and the rear frame is a position closer to the clamper than the seals.