A multi-processing system includes: a selecting unit that selects a clock frequency for each processor chips based on lot-to-lot variation thereof; a calculating unit that calculates chip performance of the processor chips operating at the clock frequencies; a judging unit that judges whether a total of chip performance of the processor chips is equal to or higher than a predetermined system performance; and a setting unit that sets the clock frequencies to the processor chips when the total is equal to or higher than the predetermined system performance.