A differential comparator which outputs positive and/or negative logic signals to an output terminal according to the coincidence/non-coincidence of first and second input signal levels inputted to first and second input terminals, respectively, comprises an offset cancel function composed of an offset capacitor device provided on the differential comparator side of the first and second terminals, a first switch for short-circuiting the first and second input terminals in such a way as to form a closed loop including the offset capacitor device, and a second switch for short-circuiting both the connection point between the offset capacitor device and the differential comparator, and the output terminal.