A communication system includes multiple communication nodes and a communication line. The multiple communication nodes include a master and multiple slaves. The communication line cascade-connects the communication nodes and supplies electricity. The communication line corresponds to a feeder line. Each of the communication nodes is connected with the communication line through an inductor to be supplied with electricity. The each of the communication nodes is AC coupled to the communication line to transmit and receive a communication signal. The master and the slaves perform a bidirectional communication. A communication slave is provided. The communication slave is connected with a communication line through an inductor to be supplied with electricity. A communication master is provided.