A plasma processing apparatus in which power consumption is reduced, which can generate uniform plasma in a large range and in which minute processing in high etching selectivity and in high aspect ratio is enabled is disclosed. High density plasma is generated in a vacuum vessel housing a processed sample utilizing an electron cyclotron resonance phenomenon caused by an electromagnetic wave in an ultra-high frequency band and a magnetic field and the surface of the processed sample is etched using this plasma. An electromagnetic wave in an ultra-high frequency band for generating plasma is radiated from a planar conductive plate consisting of graphite or silicon which is arranged opposite to the surface of the processed sample into space inside the vacuum vessel. High density plasma in the low degree of dissociation can be generated by using an electromagnetic wave in an ultra-high frequency band and as a result, the controllability of etching reaction can be enhanced. Further, a radical effective in etching can be increased by reaction between the surface of a planar conductive plate for radiating an electromagnetic wave and plasma.