In a plasma processing method for conducting etching on an object to be processed by generating plasma from depositional gas introduced into a processing chamber and exposing the object to be processed to the plasma in a state in which radio frequency power is applied, the object to be processed is etched under etching conditions that a deposit film on an inner wall of the processing chamber becomes amorphous by repeating a first period during which the object to be processed is exposed to plasma and a second period during which the object to be processed is exposed to plasma and an etching rate is lower as compared with the first period. Consequently, particles due to increase in the number of processed sheets of the object to be processed can be suppressed.