A controller of a pulse width modulation signal-driven device, includes:
an instruction input of operating the pulse width modulation
signal-driven device; a control section generating a control clock which
operates the pulse width modulation signal-driven device; a frequency
modulator frequency-modulating the control clock, to thereby give to the
control clock a frequency variation in a predetermined frequency range; a
frequency varier generating a modulation signal inputted to the frequency
modulator; and a first switching member driving the switching element
which flows a predetermined drive current to the pulse width modulation
signal-driven device based on the frequency-modulated control clock. The
frequency varier includes: a first signal generator setting a range of
diffusing a switching noise in a frequency range, and a unit for shifting
a frequency band of the switching noise by giving a predetermined offset
voltage to an output voltage of the first signal generator.