In the present invention, a PLC device is provided with a main unit for performing communication over an electrical power line, and an attachment part provided integrally with the main unit. The main unit converts an electrical-power-line communication signal received via electrical-power-line communication from an electrical power meter having a communication function to a wireless signal for wireless transmission to a predetermined device (instrument-management device). The attachment part is a member for attaching the main unit to a device (such as a trunk breaker) inside a distribution board.
