A plasma processing apparatus is for performing plasma processing in a depressurizable inner space. The apparatus includes a chamber having therein an inner space, a supporting table provided in the inner space and configured to support a substrate to be mounted thereon, one or more first members included in the chamber or separate from the chamber and partially exposed to a depressurized environment including the inner space, and one or more second members included in the chamber or separate from the chamber, each being in contact with a corresponding one of said one or more first members, and partially disposed in an atmospheric pressure environment. The apparatus further includes one or more feeders each of which is configured to supply a coolant to a cavity formed in a corresponding one of said one or more second members.