To provide a comparator circuit which is improved in the capability of outputting pulses having the same cycles as input pulses having a short pause period while having the capability of preventing malfunction.

The comparator circuit 10 comprises: a charging and discharging circuit 100 which alternately charges and discharges a capacitor 105 with charging and discharging currents in response to switching of an input pulse signal; a comparator circuit 200 which compares the capacity voltage (Csig) of the capacitor 105 with a first threshold voltage (Vth1) and a second threshold voltage (Vth2) larger than the first threshold voltage respectively to generate a pulse signal corresponding to comparison results and outputs the pulse signal as a signal for switching the level of an output pulse signal to an output signal generating circuit 550; and a logical processing circuit 300 which generates a signal for adjusting current values of the charging and discharge currents of the charging and discharging circuit 100 from the generated pulse signal, and outputs the signal to the charging and discharging circuit 100 to adjust the current values of the charging and discharging currents.