A communication system includes a transmission path and multiple nodes. At least one of the multiple nodes includes a second communication portion and a control portion in addition to a first communication portion. When the control portion performs a high speed communication, the control portion shifts the first communication portion included in each of the remaining multiple nodes to a sleep mode. The second communication portion performs a differential communication at a higher speed than the first communication portion using a differential signal. In the differential signal, a maximum of a potential difference between the pair of communication lines is equal to or less than a recessive threshold value, and a minimum of the potential difference between the pair of communication lines is a negative voltage value that has a polarity opposite to the recessive threshold value of the first communication portion.