PURPOSE: To monitor a plurality of sets of air guns individually adjust the oscillation time of the air gun by detecting an through an exclusively used sensor the oscillation in the oceanic research.

CONSTITUTION: The oscillation of the air gun 1 which is pulled by ship 3, and radiates the explosive sound into the sea due to the oscillation phenomenon in which the air of high pressure stored in the inside is opened instantaneously. In this case, the oscillation transmission medium 5 using the pulling cable 2 made of steel disposed between the oscillation sensor 5 and the air gun and the sensor 5 detecting the oscillation and emitting the corresponding signal is provided and according to the signal, the oscillation of the air gun is detected. In addition, there are disposed circuitry systems 9, 10 for oscillating the air gun at a predetermined internal and a circuitry system 8 for detecting the faulure of the air gun 1 when the oscillation at a predetermined interval is not produced.