In a method of scheduling tasks for controlling hardware devices, a specified task having the execution right in a current time slice is terminated by depriving the execution right therefrom, when a time during which the execution right continues reaches the activation time given to the specified task. An identification process is performed when each reference cycle has been completed or each task has been terminated. In the identification process, i) when there remain, time-guaranteed tasks which have not been terminated in the current time slice, a time-guaranteed task whose priority is maximum among the remaining tasks is identified, and ii) when there remain no un-terminated time-guaranteed tasks in the current slice, of remaining non-time-guaranteed tasks which are not terminated yet in the current time slice, a non-time-guaranteed task whose priority is maximum is identified. The execution right is assigned to the identified task through the identification process.