PURPOSE: To provide a count value setting circuit for monitoring writing data in respect to a counter circuit for changing various count values in a data processor.

CONSTITUTION: The count value setting circuit is constituted of a counter 1 for starting count from set data, an initial data part 2 having initial data for the counter 1, a set point monitoring part 3 for judging the validity/invalidity of set data outputted from a central processing unit (CPU) 7, a data setting part 4 for writing set data outputted from the CPU 7 based upon a judged result outputted from the monitoring part 3, and a switching control part 5 for sending a switching signal to a switch 6 when data to be written in the setting part 4 are correct and controlling switching so that the initial data outputted from the initial data part 2 are switched to the set data outputted from the setting part 4.