According to one embodiment, an edge ring is provided which includes a first movable portion provided along an outer circumference of a support portion having an upper surface capable of holding a semiconductor substrate thereon, the first movable portion being movable in a direction perpendicular to the upper surface; a second movable portion provided along an outer circumference of the first movable portion, the second movable portion being movable in the direction; and a driving portion capable of moving the first movable portion in the direction by way of the second movable portion.