A method of scheduling a CPU in which a clock of the CPU is controlled depending upon the states of processes to reduce power consumption. The clock is controlled by substituting clock functions of an embedded system into a scheduler function, comparting a wait time until a scheduling is completed with the sum of an execution time given for satisfying a real-time condition and an error range of a permissible error of a scheduling, changing a clock state of a process depending on the compared result, calculating an elapsed time with respect to a difference between the changed scheduling clock and a scheduling clock before the change of clock to control the wait time Wk and setting the clock of the CPU using the value of a newly determined clock.