In a plasma processing method includes a first stage of generating plasma of a first processing gas and a second stage of generating plasma of a second processing gas, are performed, a time difference between a start time point of a time period during which the second stage is performed and a start time point of an output of the second processing gas from a gas supply system is decided automatically according to a recipe. A delay time corresponding to flow rates of the first processing gas and the second processing gas in the second stage is specified from a function or a table.