PURPOSE: To shorten a testing period and to reduce testing cost by performing the rainfall test of the radome mounted on an airplane.

CONSTITUTION: The compressed air equal to that acting on an airplane in a flight state is supplied to an air nozzle 5 under pressure from a compressed air supply means 1 and water is mixed with the compressed air injected from the air nozzle 5 while increased in its velocity from a water nozzle 6 to generate waterdrops. The amount of the waterdrops is controlled by a shutter dome and the waterdrops passing through the shutter dome 9 are showered upon a radome 11. A wind and rain state at the time of light is formed on the ground through ejector effect and the utilization of the shutter dome 9 to make it possible to perform the rainfall test of the radome 11 and the shortening of a testing period and a decrease in testing cost are achieved.