Plasma processing apparatus and plasma processing method

A plasma processing apparatus (1) performs plasma etching of a film to be processed on a wafer (16) in which a plurality of layers of films, in which insulating films and metal-containing films to be processed are alternately laminated, are formed on a substrate. The plasma processing apparatus (1) comprises: a processing chamber (10) disposed in a vacuum container; a sample stage (14) which is disposed in the processing chamber and on which a wafer is placed; a detection part (28) that detects reflected light reflected by the wafer from the light irradiated to the wafer; a control part (40) that controls plasma processing on the wafer; and an end point determination part (30) that determines an end point of etching on the film to be processed on the basis of a change in the amplitude of the vibration in the wavelength direction of the spectrum of the reflected light, the control part stops plasma processing on the wafer by receiving the determination of the end point by the end point determination part. 等离子处