A magnetic disk device is removable from an apparatus body includes a case, a driving unit, and a connector. The driving unit is installed in the case, and includes a magnetic disk and a rotary driver for rotationally driving the magnetic disk. The connector connects the driving unit and the apparatus body. The case includes an elastic supporting member and a locking member. The elastic supporting member elastically supports the driving unit. The locking member is movable between a locked position and an unlocked position, the driving unit being locked at the locked position and being unlocked at the unlocked position in the case. The locking member moves to the locked position and the unlocked position by operational force from the exterior of the case.