Herein disclosed a digital image sender for transmitting a digital image signal including image signals for color image reproduction, a reference clock signal and parallel control signals, including: a parallel/serial converter configured to convert the parallel control signals into a serial control signal by time division multiplexing; a superposition element configured to superpose the serial control signal obtained by the conversion by said parallel/serial converter on the reference clock signal and output a resulting superposition signal; and an electro-optic converter configured to convert the superposition signal outputted from said superposition element from an electric signal into an optical signal.