Vehicle multiplex communication system

That the information communication is performed between a vehicle multiplex communication system in which a particular communication node and ordinary communication nodes are connected to a multiplex communication line and arranged such via the multiplex communication route, wherein: The ordinary communication nodes each include ordinary transmission means include first information that a communication-continuing request flag (Flag = 0, Flag = 1), which indicates whether the own node ongoing communication asks (Flag = 1), to the to provide multiplex communication route, and include sleep-transition control means to cause the own node enters the idle state; and the particular communication node instruction means includes, to provide a sleep-transition command signal to the sleep-transition control means when the communication-continuing demand flag indicating that the own node inquires no ongoing communication (Flag = 0 ).