PURPOSE: To secure the comparison operation of a comparator circuit and to improve the precision of a comparison circuit by distributing the time for operating first and second switch means to first and second operation modes.

CONSTITUTION: At the time of the operation of a circuit, a system is distributed to the operation modes M1 and M2, which are synchronized with a basic clock . At the time of the mode M1, a holding means 30 is charged to input Vi1, and an output means 40 is reset so that comparison output So is fixed to prescribed potential. At the time of the mode M2, an auxiliary switch means 50 is turned off by a state where a switch means 10 is turned off at the comparison operation mode at the time of the mode M2, and the switch means 20 is turned on. Thus, input Vi2 is supplied to the holding means 30 charged to the voltage value of input Vi1, and the holding means 30 is furthermore charged or discharged according to whether the voltage value is higher or lower than input Vi1. The potential of the input-side of the output means 40 is changed by the change and the means 40 is set to be 'H' or 'L' in accordance with the direction of the potential change of comparison output So.