An index generating unit divides each name data of search target data both into words and into characters, calculates start and end scores showing a start and an end of each of the words and start and end scores showing a start and an end of each of the characters, links them to each entry word which constructs the name data as a list (a name ID, a position, and start and end scores), and stores this list in an index storage unit. A searching unit decomposes an input character string into partial character strings, acquires corresponding candidate entries from the index storage unit, and judges the continuity between candidate entries on the basis of lists to add a comparison score according to the continuity to a candidate entry.