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. 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 in the ceramic dielectric substrate and is opposite to the gas feed channel. The first porous part includes a first porous region, and a first dense region denser than the first porous region. The first porous region includes first sparse portions, and a first dense portion. The first sparse portions include pores. The first dense portion has a higher than the first sparse portions. The first dense portion is positioned between the first sparse portions. The first sparse portions include a first wall part provided between the pores.