According to the embodiment, an electrostatic chuck includes a ceramic dielectric substrate having a first major surface placing a suction object, a second major surface on an opposite side to the first major surface, a base plate supporting the ceramic dielectric substrate and including a gas introduction path, and a first porous part provided at a position between the base plate and the first major surface of the ceramic dielectric substrate and being opposite to the gas introduction path. The first porous part includes a first region positioned on the ceramic dielectric substrate side. The ceramic dielectric substrate includes a first substrate region positioned on the first region side. The first region and the first substrate region are provided in contact with each other, and an average particle diameter in the first region is different from an average particle diameter in the first substrate region.