Abstract: A data inspecting device displays each of a plurality of data individually indicated as a mark which can be reproduced by a reproducing element and which has a length, so that the data inspecting device makes it possible to inspect a plurality of the data. The data inspecting device is provided with a calculating element for calculating the degree of mutual relevancy to predetermined kinds of parameters at different length points between one group of data which the reproducing element is reproducing out of a plurality of the data and the other groups of the data except such one group of the data and a display element for displaying the mark indicative of each of the other groups of data corresponding to the point in a different mode of display in accordance with the calculated relevancy. This makes a user recognize more accurately the relevancy of the mutual data.