A retainer includes a frame, a pair of first elastic parts projected from a pair of opposing parts of the frame so as to approach to each other, and a second elastic part that is supported at the bent free ends of the paired first elastic parts to hold a substrate. The outside end of the second elastic part is positioned outside the free end of the first elastic part and closer to the opposing part of the frame. Also, first and second holds for holding the rim of the substrate are formed apart from each other. The second hold is positioned on the outer end side of the second elastic part from the first hold.