A PWM signal generator section for generating a plurality of PWM signals with different phases to be respectively fed to a plurality of loads, and a phase difference setting section for setting phase differences among the PWM signals are provided. The phase difference setting section sets phase differences Δt_shift(n,n+1) calculated based on an effective current Ia(n) flowing to each of the loads, where the number of the loads is N, according to the equations below: Ia_all = ∑ n = 1 N ⁢ Ia ⁡ ( n ) ⁢ t_shift ⁢ ( n , n + 1 ) = t_pwn × Ia ⁡ ( n ) / Ia_all where n=1 to N (where N is an integer of two or more, and n+1=1 when n+1>N), and t_pwm is a cycle of the PWM signals.