When digital signals are to be transmitted between a camera unit and a camera control unit, the distance of their transmission depends on the frequency at which the digital signals are transmitted. The higher the frequency of the digital signals is, the greater the cable attenuation is, inviting deterioration of the signals. Therefore, with a view to matching the quantity of transmitted signals with the length of the transmission path and thereby achieving high quality of signal transmission, a method of signal transmission for a signal transmission apparatus wherein a camera unit and a camera control unit for controlling the camera unit are connected by a transmission path and a video signal, an audio signal and a control signal are digitized, time division multiplexed and transmitted between the camera unit and the camera control unit, has a step of measuring the value of delay of signals transmitted over the transmission path, and each of the camera unit and the camera control unit performs a step of controlling the data quantity of signals to be delivered to the transmission path on the basis of the measured value of delay.