The present invention provides a light emitting device that can attain standardization of the whole system, reduction of the number of mounting steps, and cost reduction using a feed line as a communication line. The control unit 12 and respective light units 14, 16 and 18 are connected through feed lines 20, 22, 24 and 26. The switching elements 32, 34 and 36 are installed in the feed lines 20, 22, 24 and 26. The PWN signals are applied to each switching element 32, 34 and 36 by the controller 30 of the control unit 12 to control the ON/OFF operation of the switching elements 32, 34 and 36, therefore the lighting, blacking out and dimming of the light emitting diodes LED1, LED2 and LED3)of respective light units 14, 16 and 18 can be controled without the other communication wire except the feed lines 20, 22, 24 and 26.