A plasma processing apparatus is provided which processes a sample held on a sample table arranged in a process chamber in a vacuum container by using a plasma formed in the process chamber. The plasma processing apparatus comprises: paths arranged in the sample table in which a coolant is supplied and vaporized as it flows; a refrigeration cycle having the sample table, a compressor, a condenser and an expansion valve connected in that order and having the coolant circulate therein; coolant passages to cause the coolant that has passed through the expansion valve to branch and then merge with a coolant returning from the paths in the sample table toward the compressor; and a regulator to adjust an amount of coolant passing through the paths in the sample table and circulating in the refrigeration cycle and an amount of coolant branching and flowing through the coolant passages.