An electrostatic chuck includes a ceramic dielectric substrate; a base plate; and a heater unit which heats the ceramic dielectric substrate. The heater unit includes first and second heater elements. The second heater element has a plurality of main zones separated from each other in a radial direction. The first heater element has a plurality of sub-zones separated from each other. A number of the sub-zones is larger than a number of the main zones. The main zones include a first main zone. The first main zone has a main heater line and a first main power feeding portion. The sub-zones include a first sub-zone overlapping the first main zone. The first sub-zone has a central region and an outer peripheral region. The first main power feeding portion is provided at a position where the first main power feeding portion overlaps the central region.