PURPOSE: To eliminate a waste of the latency time by controlling plural record blocks, to which one round of a storage medium of a fixed head type magnetic disc device or magnetic drum device is divided, as one storage section.

CONSTITUTION: One round of a storage medium 7 is divided to (n) record blocks. Supposing that the rotation position of the storage medium 7 corresponds to the beginning part of a formalized track 17a, respective objective records (e), (f), (g), and (h) of record numbers R1, R3, R4, and R5 are processed as shown by 18 when record numbers R1, R3, R4, and R5 out of record numbers R1WRn accept already a storage control instruction. Thus, a recording or reproducing request for objective records whose quantity is equal to the division number of record blocks of the storage medium is processed within a time required for one rotation of the storage medium. Further, processings of objective records are not queued because this storage medium can be rotated synchronously.