In a plasma processing method, a correlation between substrate type data and optical data is obtained by using a multivariate analysis; substrate type data is obtained from optical data based on the correlation when initiating a plasma processing; and a substrate type is determined by using the obtained substrate type data. Further, a setting data set corresponding to the determined substrate type is selected from setting data sets, each for detecting a plasma processing end point of the plasma processing, each of the setting data sets being stored in advance in a data storage unit; an end point of the plasma processing is detected based on the selected setting data set; and the plasma processing is terminated at the detected end point.