A data communication system including reflectors having first light emitting elements for radiating light and first light receiving elements for receiving light, a plurality of transceivers disposed confronting said reflectors and having second light emitting elements for radiating light and second light receiving elements for receiving light, and a data processing unit to be connected to the transceivers, wherein light corresponding to the data to be transmitted from the data processing unit is converged and radiated from the second light emitting element of the transceiver to the reflector, the light from the transceiver is received by the first light receiving element of the reflector, light corresponding to the data thus received is radiated from the light emitting element of the reflector to all of the transceivers confronting said reflector and is received by the second light receiving elements of the transceivers, and the data thus received is sent to the data processing unit.