To provide a plasma processing apparatus which can detect the terminal point of the plasma processing with sufficient accuracy, and to provide a plasma processing method which can raise the quality of the plasma processing.

While impressing voltage to electrode members 12 and 13 disposed opposite to each other from a power supply 7, and generating plasma gas 4a by passing processing gas 4 between these electrodes, a plasma processing apparatus 1 which brings the plasma gas into contact with the surface of a glass substrate 2 as material to be processed so as to perform etching processing is provided with a laser displacement 20 which detects the boundary plane of the glass substrate 2 and a thin film 2a as a base level of the glass substrate 2. During the etching processing, the amount of displacement of a boundary plane is detected from an incidence light 21 and a reflection light 22 which are irradiated from this laser displacement meter, and a terminal point of etching processing is detected based on the variance of a detection value.