PURPOSE: To automatically release discordance of ID codes by providing between an electric lock and an electric lock controller a repeater equipped with a non-volatile memory for storing ID codes, and locking or dislocking a door via the repeater.

CONSTITUTION: An electric locking system comprises a repeater B interposed between an electric lock C and an electric lock controller A. The repeater B is formed by an I/F portion 2 for transmitting and receiving signals to and from the electric lock controller A, a light transmitting portion 2, a light receiv ing portion 4, an indicator 5, a controlling portion 1 comprising a CPU for signal processing, an oscillator 7 and a non-volatile memory a for storing ID codes. In changing ID codes, the system judges when an ID code does not accord with that stored in the memory 8 and there is no error that it is only the ID codes that do not accord with each other, and resends a signal requiring an ID code to be stored. Thereby transmission of a normal signal is possible even with mistakes in the setting of the codes.