1. An information classifying device, comprising: distance calculating means for calculating distance information between each of an arbitrary number of pieces of sample information and center of gravity of each of an arbitrary number of populations including said pieces of sample information, using a distance evaluation function; statistical information calculating means for calculating statistical information using mean of sample distances and variance of sample distances with the mean of sample distances being the center, based on each group of distance information constituted by said distance information calculated by said distance calculating means, associated with each said sample information belonging to each said population; degree of assignment relevancy evaluating means for evaluating degree of assignment relevancy, by calculating distance between the center of gravity of each said population and sample information as an object of classification using said distance calculating means, normalizing said distance using said statistical information calculated by said statistical information calculating means on said calculated distance and performing a statistical test; assignment destination determining means for determining to which population said piece of information as the object of classification is to be assigned, according to the degree of assignment relevancy evaluated by said degree of assignment relevancy evaluating means; and sample information classifying means for assigning and classifying said piece of sample information as the object of classification to the population determined by said assignment destination determining means.