The invention provides a 
plasma processing apparatus comprising a means for detecting the apparatus condition related to the 
ion flux quantity of 
plasma (
plasma density) and the distribution thereof for to stabilizing 
mass production and minimizing apparatus differences. The 
plasma processing apparatus comprises a vacuum reactor 108, a 
gas supply means 111, a 
pressure control means, a plasma source power supply 101, a lower 
electrode 113 on which an object to be processes 112 is placed within the vacuum reactor, and a 
high frequency bias power supply 117, further comprising a probe 
high frequency oscillation means 103 for supplying an oscillation frequency that differs from the plasma source power supply 101 and the 
high frequency bias power supply 117 into the 
plasma processing chamber, high frequency receivers 114 through 116 for receiving the high frequency supplied from the probe 
high frequency oscillation means 603 via a surface coming into contact with plasma, and a high 
frequency analysis means 110 for measuring the impedance per oscillation frequency within an electric circuit formed by the probe 
high frequency oscillation means 603 and the receivers 114 through 116, the reflectance and the 
transmittance, and the variation of 
harmonic components.