Plasma processing apparatus and plasma processing method

The invention provides a technique for accurately detecting partial separation from a mounting table of a substrate regardless of the size of a substrate when performing plasma processing. In a plasmaprocessing apparatus, a DC voltage is applied to an electrostatic attraction electrode, a glass substrate is electrostatically attracted to the mounting table, and separation of the glass substrate from the mounting table is detected by a change in a DC voltage, and the plasma processing apparatus can measure a DC voltage applied to the electrostatic attraction electrode and acquires a voltage measurement value. Further, a difference value between the voltage measurement value and the applied voltage setting value is obtained, and a difference value is amplified to obtain a difference amplification value. Then, the difference amplification value is compared with a threshold value, and when the difference amplification value exceeds the threshold value, application of high-frequency powerto generate plasma is stop