To prevent both overetching and underetching, even if a variation of emission intensity is not constant, at termination point detection in plasma etching process.

In a determination method of termination point in a plasma treatment, a termination point is determined at etching treatment, when the etching treatment is carried out for single wafers, an etching termination time of the wafer which has been processed immediately prior to is detected and feed-backed, and then it is used as a guard time of the termination determination in the etching treatment thereafter. Since the etching time is limited by the guard time within the prescribed range, even if the difference is caused in the termination determination of the etching treatment by emission intensity, over-etching and under-etching are canceled.