Abstract: A data managing apparatus includes a data file storing records each including data units corresponding to predetermined items, and an index file corresponding to a certain item which requires data arrangement in a predetermined sequence and storing change bits each corresponding to one of the records stored in the data file and each representing whether data has been changed between the adjacent records with respect to the corresponding item. When a retrieval request is received from an operator about the foregoing certain item, the change bits are read from the index file following a retrieval start position and a retrieval direction designated by the retrieval request, so that a requested record is identified based on the read change bits. Then, data units of the identified record are read from the data file and notified to the operator via a display device or the like.