In an apparatus to be controlled 20 such as a USB-compatible peripheral device connected to a controlling apparatus such as a personal computer, when a specification change is detected such as a change in the apparatus to be controlled 20 itself and a change in the connection situation of an attached device 30 (S201: YES), identification information corresponding to the changed specification is extracted (S205) and the extracted identification information is set as identification information to be transmitted to the controlling apparatus 10 (S206). The identification information having been set is transmitted to the controlling apparatus 10, and the controlling apparatus 10 controls the apparatus to be controlled 20 having the changed specification, on the basis of the identification information. This controlling apparatus for controlling the apparatus to be controlled on the basis of the identification information for identifying the apparatus to be controlled adjusts easily to the change in the specification of the apparatus to be controlled.