A control device capable of appropriately switching operating modes when multitasking is being performed is provided. A CPU unit is provided with a task executing unit for executing a plurality of tasks in parallel, and for executing each task in cycles based on each task; and a mode switching unit for switching operating modes. The task executing unit is configured in such a manner that when in operation mode, a user program is executed for each task, and when in program mode, a user program is not executed for each task. The mode switching unit is configured in such a manner that the operating mode is switched when a plurality of tasks being executed by the task executing unit are synchronized