PURPOSE: To improve the monitoring property and improve safety in various monitoring services by providing a means displaying a monitoring image and the relevant information to the image concurrently on the same screen.

CONSTITUTION: This monitoring device is provided to transmit the state near a connection section as image information to a connecting vehicle 1a during the division or connection of the vehicle organization and to support the judgment during a driving operation, and a video camera 3 photographing the preset range including the coupler 2b of a connected vehicle 1b stopping at a fixed position on the ground and a light transmitter 4 converting the video signal from the video camera 3 into a light signal and transmitting it to the receiver 6 reproducing image information from the light signal and outputting it, and distance measuring device 10 detecting the distance between the vehicles 1a, 1b, a picture synthesizing device 8 generating a picture synthesized with the display signal generated by a data processor 7 and the image information, and a display monitor viewer 9 are provided on the vehicle 1a side.