A plasma processing method for processing a sample by using plasma on a lot unit basis, including: detecting plural kinds of information as monitor data relating to a processing state of the sample, using a plurality of sensors; selecting a detection time range of the monitor data thus detected; converting the monitor data within the selected detection time range into a converted signal; predicting a pattern shape of the sample based on the converted signal; calculating a correction quantity of a processing parameter, for decreasing a deviation between the predicted pattern shape and a standard value; and converting the correction quantity of a processing parameter obtained by the calculating operation when a kind of a next sample of a next lot is different from the sample, thereby to use a converted correction quantity of the processing parameter for a processing of the next sample.