To prevent a misread due to an illegal positioning by logically disabling data to be reproduced when a track other than a target track is accessed.

To the storage device controller 101, a data bus 108 administering a data communication with a SCSI I/F 102 and a data bus 109 which administers a data communication with a storage device 103 are connected. The controller 101 which controls this storage device 103 is provided with a function of recording in the storage device data to be recorded in the storage device 103 after EX-ORing it with scramble data comprising the track number of a target physical track to be accessed and a head number. Further the controller 101 is given a function of host transfer of data reproduced from the storage device 103 after EX-ORing it with the scramble data comprising the track number of the target physical track to be accessed and the head number.