There is provided the substrate holder for holding a substrate comprising a first holding member, a second holding member, a sealing member, a pin, a ring, and a moving mechanism. The sealing member forms a sealed space inside the substrate holder. The pin is fixed to one of the first holding member and the second holding member. The ring is disposed on another of the first holding member and the second holding member. The ring engages with the pin. The moving mechanism circumferentially moves the ring. The pin and the ring are engaged with one another to fix the first holding member and the second holding member to one another. The pin and the ring are disposed inside the sealed space.