In an endoscopic diagnosing system, signals are exchanged using radio waves at between an electronic endoscope, an operator's processor unit and a director's processor unit. The director's processor unit has a transmitting section that modulate into and transmit a radio wave an operation input signal inputted through a zooming button of an operation input device, and a video-signal processing section that switches display over between split screen to display endoscopic images separately between a plurality of electronic endoscopes on the director's monitor and full screen to display one endoscopic image fully on the director's monitor.