A pulse width modulation (PWM) converting circuit includes a pulse generator for generating two pulse signals for each bit of a basic clock pulse train, in response to the value of digital input data, and a differential amplifier for outputting a differential amplification component between the two pulse signals as a PWM signal. The pulse generator varies pulse width of a first of the two pulse signals, on a bit-by-bit basis, of the basic clock pulse train, in response to the value of the digital input data, and holds a level of a second of the two pulse signals throughout all of the bits of the basic clock pulse train, within the period of the pulse of the PWM signal.