Provided is a plasma processing apparatus which comprises a chamber, a stage configured to set a holding sheet and a substrate held thereon, a securing mechanism configured to secure the holding sheet on the stage, a plasma generator including a first electrode and a first high-frequency power supply, and a determiner for determining a contact status between the holding sheet and the stage, wherein a gas through-hole is arranged on a surface of the stage in an annular region defined between an inner edge of a frame set on the stage and an outer edge of the substrate, and wherein the determiner is configured to determine the contact status in accordance with a pressure of a gas in the gas introduction conduit and/or a regulation data for regulating the pressure of the gas, the gas being introduced between the stage and the holding sheet from the gas through-hole.