PURPOSE: To compensate an offset voltage due to the field through charge of an analog switch and to attain high accuracy by open/close-controlling a first analog switch and a second analog switch and holding an input signal to a first capacitor.

CONSTITUTION: When the first analog switch 3 is closed, the input signal is charged to a capacitor 5, a sampling action is executed, on the other hand, the second analog switch 6 is opened with a delay by the degree of a first period, and the field through charge of the switch 6 is charged to the capacitor 6. Next, when the switch 3 is opened and a change to a holding action is executed, the field through charge is charged to the capacitor 5 in being superimposed on a signal charge. When a third period passes, the switch 6 is closed, the field through charge of the switch 6 charged to the capacitor 6 is set to a node 11 side, and the field through charge of the switch 3 charged to the capacitor 5 is offset. Thus, the offset voltage due to the field through charge is compensated, and the high accuracy can be attained.