To enable other companies to use each independently developed application by transmitting a control signal, which includes preliminarily determined cipher information and has a prescribed format, from an apparatus on the control side and setting the application to the executable state by an apparatus on the controlled side in the case of reception of the control signal including preliminarily determined cipher information.

When receiving a target key code from a target (2), a controller multiplies a cipher function by this target key code to calculate an application key code. An open command of the application to which the application number and the calculated application key code are added is transmitted to the target (3). The target confirms whether the decoded result is equal to its own target key code or not; and if it is equal, the target validates the open command of the application K and enters into the open state that the application can be executed.