The invention aims at providing a plasma processing apparatus capable of removing the deposition film in the processing chamber and suppressing the corrosion of wall surface material. The plasma processing apparatus for subjecting an object to be processed to vacuum processing by introducing a processing gas into a processing chamber 101 and generating plasma 110 comprises plasma generating means 106 through 108, a monitor means 112 for detecting the existence of a reaction product containing a material constituting an inner wall 102 of the processing chamber, and an alarm means for notifying that the existence of the reaction product containing the material constituting the inner wall 102 of the processing chamber has exceeded a predetermined amount, wherein a plasma cleaning is performed for every arbitrary etching process, and a wall surface stabilization process is subsequently performed using O2 gas or F gas.