Electrostatic chuck and semiconductor manufacturing apparatus

An electrostatic chuck provided with a ceramic dielectric substrate and a base plate, the electrostatic chuck being characterized in that the ceramic dielectric substrate has: first and second main surfaces; a groove portion recessed from the first main surface to the second main surface; and a plurality of cooling gas holes penetrating between the groove portion and the second main surface, the groove portion having first and second circumferential grooves and first and second radial grooves, the plurality of cooling gas holes having: a first hole overlapping the first radial groove in plan view; and a second hole that overlaps the second radial groove in plan view, the base plate having a gas introduction path that supplies a cooling gas to the first hole and the second hole, the first circumferential groove having a first end located on one end side in the circumferential direction and a second end located on the other end side, and the second circumferential groove having a third end located on one end si