PURPOSE: To drastically reduce a time necessary for testing by constituting the system so that plural CAPTAIN terminals can be connected to one center unit.

CONSTITUTION: An image information retrieval signal from one 6a of the plural CAPTAIN terminal equipments 6a∼6n is made effective in a second hybrid circuit 4a and is transmitted to the center unit via a first hybrid circuit 1. An image information transmitted from the center unit corresponding to the image information retrieval signal is distributed to plural level adjusting amplifiers 2a∼2n from the first hybrid circuit 1, then the distributed signals are, after level adjustment, transmitted to the connected plural CAPTAIN terminal equipments via second or third hybrid circuits 4a∼4n, and thus the same image information are displayed. In such a way, the same image information are displayed in all the CAPTAIN terminal equipments by means of only one image information retrieval signal from one terminal equipment, hence a testing time can be drastically shortended.