A PLC/power-supply hybrid device includes a power supply circuit. The power supply circuit includes a switching part for chopping a voltage of a voltage input terminal side, and a control circuit that controls the chopping by controlling switching of the switching part. The control circuit is operated in a normal mode and a transmission mode. The normal mode is a mode in which voltage conversion is performed. The transmission mode is a mode in which data transmission is performed through PLC using a power line that leads to the voltage input terminal. In the transmission mode, the control circuit modulates the switching of the switching part in accordance with transmission data.