In an electronic apparatus control system provided with: a plurality of electronic apparatuses connected to a network covering a predetermined area; and a controller for controlling these electronic apparatuses, the controller (11) is provided with: a generating device for generating a group key peculiar to the network (18) in order to encrypt the information flowing through the network (18); and a wireless unit (21) for transmitting the generated group key to a plurality of the electronic apparatuses. The electronic apparatus is provided with: a memory device for storing the group key transmitted; an encrypting device for encrypting the information flowing through the network (18) using the group key; and a decoding device for decoding the encrypted information using the group key. Owing to this construction, it is possible to present a copy protection improved in the maintainability and reduced in the cost, for protecting copyright effectively even in a case that information is flown out of the network (18).