A substrate support includes a substrate support portion having an electrostatic chuck for adsorbing a substrate and a substrate heater electrode inside the electrostatic chuck; a ring support supporting an edge ring and having an edge ring heater electrode inside; a base having a central stage on which the substrate support portion is disposed, and an outer peripheral stage on which the ring support is disposed; a first power feeding terminal disposed immediately below the substrate support portion to supply a power to the substrate heater electrode; and a second power feeding terminal disposed immediately below the ring support to supply the power to the edge ring heater electrode. An upper surface of the outer peripheral stage is positioned lower than that of the central stage, and a thickness of the ring support is equal to or larger than 40% of a thickness of the substrate support portion.