The invention provides a plasma processing method capable of reducing the damage applied to the low-k film or the underlayer. The method uses a plasma processing apparatus comprising gas supply means 41, 42 for respectively supplying processing gas independently to a center area of the processing chamber 1 and to an area near the sidewall thereof; a sample mounting electrode 13 for mounting a sample W to be processed; a high frequency power supply 21 for generating plasma; an antenna 11; and a plasma generating means 17 for generating plasma in the processing chamber; the method comprising etching an insulating film on the sample W using plasma; and supplying a large flow of inert gas from the center area of the chamber while having the sample W mounted on the sample mounting electrode 13, supplying deposit removal gas to only the area near the side wall of the processing chamber 1 and controlling the plasma density distribution to thereby vary the plasma density at the center area of the processing chamber and the plasma density at the area near the side wall of the processing chamber, so as to perform a deposited film removing process for removing the film deposited on the side wall of the processing chamber.