There is provided a portable storage device which makes it possible to largely reduce time that is taken to remove the storage cartridge that is inserted and cannot be handled. A removable hard disk cartridge contains a hard disk and a control circuit for control of writing and reading of data in and from the hard disk in a casing thereof. A main unit includes an automatic loading/ejecting mechanism that receives the hard disk cartridge into a predetermined inner position within the main unit and ejects the same out from the position, and a microprocessor that controls storage operation for storing data in the hard disk cartridge. Before the automatic loading/ejecting mechanism performs a receiving operation, it is determined whether access to contents recorded on the hard disk can be gained, and when the access cannot be gained, the receiving operation by the automatic loading/ejecting mechanism is inhibited.