MIXED GAS JET SPRAY DEVICE

A first tank (12) holding sodium bicarbonate (11) and a second tank (15) holding an abrasive cleaning agent (14) are provided separately in a gas passage (8). When compressed air (A) flows through thegas passage (8) towards a spray nozzle (2), first sodium bicarbonate (11) in the first tank (12) is fed into the compressed air (A), and then the abrasive cleaning agent (14) in the second tank (15)is fed into the compressed air (A). As a result, the sodium bicarbonate (11) and the abrasive cleaning agent (14) are mixed into the compressed air (A) in prescribed proportions. Said compressed air (A) is mixed with high-pressure water (3) inside the spray nozzle (2) to become a mixed gas jet (J) and is sprayed on the outer surface (Wa) of a ship hull (W). Since variation in the proportions of the sodium bicarbonate (11) and the abrasive cleaning agent (14) contained in the mixed gas jet (J) does not occur, when peeling a coating film on the outer surface (Wa) of a ship hull (W), the mixed gas jet (J) is able to effic