PURPOSE: To prepare injection to a storage device by supplying power following the injecting operation of the storage device even when a power unit for an information processor is not turned on or power supply to the storage device is not executed.

CONSTITUTION: A hard disk drive(HDD) 7 capable of replacing a hard disk cartridge is attachably/detachably stored in a HDD fitting part 15 so that an injecting operation member 22 injects the HDD 7 from the fitting part 15 by external operation, the injecting operation is detected by a switch 6 and a CPU 8 is constituted so as to control power supply from the power unit to the HDD 7. At the time of detecting the external operation of the member 22 based on a signal outputted from the switch 6 when power supply to the HDD 7 is stopped, the CPU 8 supplies power from the power unit to the HDD 7.