A visible light multiplex communication system is presented which includes identification (ID) information and data information which can be simultaneously transmitted and received to and from a server and a plurality of clients by using visible light. Visible light ID communication and visible light data communication do not interfere with each other in the same space during visible light communication. In addition, data can be efficiently transmitted and received to and from a plurality of ID clients using visible light. In addition, visible light ID communication and visible light data communication can be efficiently performed in a state where interference between clients using different protocols does not occur in the same place. Furthermore, a specific unit that is capable of efficiently transmitting and receiving data to and from a plurality of clients by using visible light can be provided.