A banknote handling system includes an unlocking system. The unlocking system includes a camera, a first mechanical arm to which one or a plurality of keys are affixed, and a controller that determines a position of a keyhole based on an image from the camera, and controls the first arm to insert one of the one or the plurality of keys into the keyhole and turn the inserted key for unlocking. In many examples, the unlocking system is configured to unlock a banknote cashbox.