To provide a plasma processing apparatus capable of carrying out cleaning work even when a processed object is in the processing vessel, and also capable of carrying out the processing work for the processed object and the cleaning work simultaneously.

This plasma processing apparatus comprises a processing vessel having a plasma processing space and a cleaning space, a first shield 12a, and a second shield 12b as shown in the figure 2. The plasma processing of the processed object mounted on a mount means is enabled in a state wherein at least either of the first and the second shields is moved into the plasma processing space, and plasma is formed in the cleaning space in a state wherein at least either of the first and the second shields is moved into the cleaning space so that the deposit formed on at least either surface of the first and the second shield plates can be removed.