1. A data processing device for processing data included in a sequence of data obtained by sampling an analog information signal, said device comprising: (a) a plurality of computing means for generating a plurality of interpolating data by processing first and second correct data included in said data sequence; (b) discriminating means for discriminating the quadratic differential characteristic of a part of said analog information signal relating to incorrect data located between said first and second correct data; (c) selecting means for selecting one of said plurality of interpolating data on the basis of an output of said discriminating means to generate a selected interpolating data; and (d) replacing means for replacing said incorrect data with said selected interpolating data.