An information creating apparatus creates a leaf page information including one or more records with a key information to be compared with a retrieval key information inputted for retrieval of a record. The apparatus creates, based on the key information of the record included in the leaf page information, a judgment information used to judge a possibility that the leaf page information located in a position of child of the node page information located between the root and leaf page informations, and in lower positions than it, includes the record to be retrieved with the retrieval key information, and creates the node page information including the judgment information. The apparatus creates the root page information including the judgment information included in the node page information located in the positions of the child of the root page information, and stores the root, node and leaf page informations in a tree structure.