Abstract: In a real-time operating system, a plurality of tasks is grouped into blocks in consideration of the deadline times required by each task, switching between tasks that belong to the same block, is not done by the task switch of the real-time operating system, but rather is done directly by a task block scheduler, so that tasks within one and the same block are substantially treated as the same task. Only when the execution of a task belonging to a block that is different from the block of the currently executing task is to be started is the task switch used to switch between tasks, thereby reducing the load placed on the real-time operating system in managing tasks.