A pulse width modulation signal with a less distortion component that is not influenced by a common-mode noise or an offset voltage is generated. Pulse signal generation circuits 6, 7 generate pulse signals S1, S2 whose pulse widths are discharge times t1, t2 of integrators 3, 4, respectively, a PWM signal generation circuit 8 detects discharge end timings of the integrators 3, 4 based on the pulse signals S1, S2, and a pulse whose pulse width is a time between discharge end timing of one of the integrators 4 and discharge end timing of the other one of the integrators 3 is generated so as to be output as a PWM signal Spwm.