PLASMA ETCHING METHOD AND PLASMA ETCHING DEVICE

In a plasma etching method for etching a target object by plasma in a state where a pressure in a processing container having a consumable member is maintained at a constant level, variation of time for temperature decrease of the consumable member from a first temperature to a second temperature lower than the first temperature or variation of speed of the temperature decrease of the consumable member from the first temperature to the second temperature is measured. Further, a degree of consumption of the consumable member is estimated from the variation of time or the variation of speed based on information on correlation between the variation of time or the variation of speed and the degree of consumption of the consumable member.