PURPOSE: To obtain a pulse width modulation circuit with less number of parts and possible for miniaturization by supplying an input to an oscillation circuit comprising a couple of C-MOS gates connected in cascade.

CONSTITUTION: The oscillation circuit consists of gates G1, G2 connected in cascade and each comprising a C-MOS, resistors R1, R2 and a capacitor C. An input is supplied to a common connecting point between the resistors R1, R2 and the capacitor C and a pulse width modulation signal is extracted from an output terminal OUT of a C-MOS gate G2. Thus, the pulse width modulation circuit with less number of parts, comprising general-purpose parts and possible for miniaturization is obtained.