A pulse width modulation circuit includes a first electric-charge accumulator; a second electric-charge accumulator; a first current generator which generates a first current corresponding to the amplitude of an input AC voltage; a second current generator which generates a second current with a constant value; a first current supply controller which supplies the first current to the first electric-charge accumulator; a second current supply controller which supplies the second current to the first electric-charge accumulator; a third current supply controller which supplies the first current to the second electric-charge accumulator; a fourth current supply controller which supplies the second current to the second electric-charge accumulator; and a current limiter which limits the first current to a third current with a predetermined current value, if the amplitude of the AC voltage in the negative side exceeds a predetermined level.