Ensuring real-time performance of multitask control and improving the processing efficiency of a system provided with a processor processing while switching between a plurality of tasks. The system includes an execution unit executing instructions on individual tasks while switching from one task to another, a distinguishing unit executing an instruction determined to be a predetermined instruction. The system further includes a determination unit set so that on condition that the instruction to be executed is the predetermined instruction, it determines whether to allow the execution unit to execute the predetermined instruction or to perform a task switching process without executing the predetermined instruction based on a predetermined condition.