PURPOSE: To enable a retrieval in a short time by providing a hash chaining, modify chaining, and same name chaining in a name information dictionary chained from a hash table and eliminating the excessive retrieval of the hash chaining and the same judging processing.

CONSTITUTION: A name information dictionary 3 having a hash chaining 4, modify chaining 5, and name 6, and same name chaining 7, is chained from a hash table 2, the hash value of the name of an object to be retrieved is searched in order to successively retrieve the name information dictionary 3 hash-chained from the hash table 2. Then, when the coincident name 6 is found, the modify chain 5 of the pertinent name information dictionary 3 is traced in order to find the name information dictionary 3 having the same modification (name). On the other hand, when the coincident name 6 is not found, the same name chaining 7 of the pertinent name information dictionary 3 is traced in order to find the name information dictionary 3 having the same modification (name).