There is disclosed a plasma processing apparatus for processing a wafer put on a sample stage disposed in a processing chamber within a vacuum vessel by the use of a plasma generated in the processing chamber after mounting the wafer on the sample stage. The apparatus has heaters in areas of the interior of the sample stage which are divided radially and circumferentially. At least those of the heaters which are arranged in the areas located in the radially outer position include circumferentially arranged heater portions that are connected in series. The amounts of heat generated by these circumferentially arranged heater portions are adjusted.