1. A circuit of a capacitive sensor having a plurality of column lines and a row line intersecting the column lines, for detecting a change in capacitance at an intersection of a column line and a row line, the circuit comprising: code generating means for generating a code having orthogonality in time sequence to output the generated code as a column drive signal; column line drive means for driving a plurality of column lines, from among the column lines that are selected in response to the code; capacitance detecting means, connected to the row line, for detecting a voltage by converting a total sum of changes in capacitance at intersections of the selected column lines into the voltage to output the detected voltage; and decode processing means for performing a predetermined calculation on the detected voltage output from the capacitance detecting means and the code to determine a voltage value responsive to the capacitance change at the intersection.