1. A data search system, comprising: a data retrieving part for retrieving data; a classifying and arranging part for classifying and arranging data in the data retrieving part on a display screen in accordance with feature values; a ground information providing part for providing each data with ground information visualizing grounds for classification and arrangement of the data by the classifying and arranging part; and a display part for displaying each data together with corresponding ground information in accordance with classification and arrangement information from the classifying and arranging part.