A detecting device includes: multiple sensors composed with a plurality of sensor circuits arrayed on a plane, each of which generates at least one detected signal that corresponds to a distance from a surface of an object; a selector circuit which selects each of the sensor circuits and outputs the detected signal from each of the sensor circuits; a storage which stores digital data of a reference value; a digital-to-analog converter circuit which generates a reference signal that corresponds to a level of the reference value from the digital data stored in the storage; a generation circuit which generates, per each of the sensor circuits, in sequence, detected data according to a relationship of levels between the detected signal output from each of the sensor circuits selected by the selector circuit, and the reference signal generated by the digital-to-analog converter circuit; an arithmetic circuit which conducts a prescribed operation with a plurality of detected data sets generated by the generation circuit; a refresh circuit which refreshes the digital data stored in the storage, based on an operational value calculated by the arithmetic circuit; and an output circuit which conducts an output process, corresponding to the detected data generated by the generation circuit.