Abstract: An object of the invention is to provide a plasma processing method for preventing generation of deposition from an underlying metal film and attaining an anisotropic shape in hard mask etching. The plasma processing method for forming a mask using a film to be etched whose underlying layer is a metal film according to the invention includes: a first step of etching, using a plasma generated by mixed gas containing O2 gas, CHF3 gas, NF3 gas, Ar gas, and He gas, while supplying pulse-modulated radio frequency power to a sample stage on which a sample having the film to be etched is placed; and a second step of etching while supplying continuous wave (CW) radio frequency power to the sample stage after the first step. The film to be etched is a TEOS film and a silicon nitride film, and the continuous wave (CW) radio frequency power is smaller than a product of the pulse-modulated radio frequency power and a pulse-modulated duty ratio and is smaller than 50 W.