An electrostatic chuck comprises an insulating layer with an electrode embedded therein and having a surface to come in contact with a workpiece to be held. Formed on the insulating layer surface is a silicone rubber layer which is filled with reinforcing silica, but free of another filler having an average particle size of at least 0.5 .mu.m. The ESC allows for an intimate contact with a wafer and has an improved cooling capacity.