A data processing device includes a comparing unit that compares a reference signal and respective processing object signals, a count-period control unit that determines a count period to perform count processing, a count unit that performs the count processing in the count period designated by the count-period control unit, stores a count value, applies the count processing to both a subtraction element and an addition element in an identical mode of any one of an up-count mode and a down-count mode, and starts the count processing for a following processing object signal using a count value for a preceding processing object signal as an initial value, and a correcting unit that corrects digital data of a multiply-accumulate result of the plural processing object signals to digital data in which a count value is corrected.