A processor system includes a processor to execute a plurality of tasks by switching to one another, a task ID storage section to store a task ID to identify a task executed in the processor, an evaluation ID storage section to store an evaluation ID to be compared with an at least partial area of the task ID, a counter to measure a performance measurement value of a task executed in the processor, and a matching section to check a task ID stored in the task ID storage section against an evaluation ID stored in the evaluation ID storage section and operate the counter in accordance with a check result.