A locking structure for detachably mounting a storage device to a casing of an electronic device includes a carrier fixed in the casing which defines a plurality of slots. a fixing member is also included, and an enclosure defining a plurality of positioning shafts corresponding to the slots which are configured to hold the storage device. A rotating frame is connected with the enclosure and a handle is connected with the rotating frame, the rotating frame including a hook engaged with the fixing member. When the handle is pulled to disengage the shafts from the slots and detach the hook from the fixing member, the storage device can be removed from the electronic device.