A clock-signal generating unit generates temporally-continuous clock signals. A spread-spectrum clock-signal generating unit generates a spread-spectrum clock signal by modulating a frequency spectrum of a clock signal generated by the clock-signal generating unit. A signal delaying unit generates a fixed delay unaffected by a spread spectrum from the spread-spectrum clock signal generated by the spread-spectrum clock-signal generating unit, and delays a phase of the spread-spectrum clock signal based on an amount of the fixed delay.