A pulse width modulation circuit of the present invention includes: pulse generation means being provided with a first power supply and charged with a first current and a second current between which a constant current is distributed to turn ON/OFF a switching element, thereby generating a pulse from a first output section; pulse modulation means for controlling the charging while controlling a distribution ratio between the first current and the second current based on an input signal, thereby changing a pulse width of the output pulse; and first short circuit means for shorting the first output section with the first power supply when the pulse being output from the first output section transitions to a voltage of the first power supply.