Disclosed is an electrostatic chuck including a circular placing region configured to place a processing target object thereon. The placing region includes a bottom surface and a plurality of protrusions configured to protrude from the bottom surface. Further, the plurality of protrusions is formed at a plurality of positions set at a regular interval on each of a plurality of circles set concentrically and at a regular interval around a center of the placing region. Furthermore, among the plurality of positions, a plurality of positions set on each of any two adjacent circles is set not to be positioned on the same straight line extending from the center.