A comparator circuit according to an embodiment of the present invention includes a comparator configured to compare an input signal voltage with a reference voltage obtained by smoothing the input signal by use of a resistor and a capacitor, and output a result of the comparison, a discharge circuit configured to compare a first addition signal which is obtained by adding a positive first voltage to the input signal voltage, with the reference voltage, and discharge the capacitor when the first addition signal is lower than the reference voltage, and a charge circuit configured to compare a second addition signal which is obtained by adding a negative second voltage to the input signal voltage, with the reference voltage, and charge the capacitor when the second addition signal is higher than the reference voltage.