A substrate holder has a first holding member having a first surface configured to contact with a substrate, and a second holding member for sandwiching and holding the substrate together with the first holding member. The first holding member has a positioning member for positioning the substrate in contact with the first surface at a prescribed position of the first surface. The positioning member is configured to move between a first position where the substrate is to be positioned at the prescribed position of the first surface, in contact with a peripheral edge part of the substrate, and a second position not in contact with the substrate. The second holding member has a driving member configured to cause the positioning member to be positioned at the first position, at the time when holding the substrate by the first holding member and the second holding member.