According to one embodiment, an electrostatic chuck includes a ceramic dielectric substrate, a base plate, and a first porous part. The ceramic dielectric substrate includes first and second major surfaces, and at least one groove. The second major surface is opposite to the first major surface. The base plate supports the ceramic dielectric substrate and includes a gas feed channel. The first porous part is provided between the groove and the gas feed channel. The ceramic dielectric substrate includes holes communicating with the groove and the gas feed channel and piercing the ceramic dielectric substrate in a first direction from the base plate toward the ceramic dielectric substrate. The first porous part includes at least one porous region including pores, and at least one dense region denser than the porous region. The porous region further includes at least one dense part.