In the monitor device 20, a liquid crystal display as a display unit 25, the liquid crystal display driving board 30 for controlling the 25 and, with the gap between the driving substrate 30 facing each monitor substrate 29 and, disposed in the gap between the driving substrate 30 and the display substrate 29 and electrically to the holder 28 and the driving substrate 30 and the monitoring substrate 29 made of resin for holding the LCD 25 having a flat cable 35 for connection with, and the holder 28 is formed with a cable insertion tonggu 62 through insertion of the flat cable 35, the cable insertion tonggu 62 within the width of the flat cable to be inserted parallel to the direction, and are also the first and second restricting portion (63, 64) spaced apart in the longitudinal direction of the cable installation.