To optimize gas flow and to improve the cooling capacity by forming gas suction holes at the rear part of cooling nozzles for discharging cooling gas.

In this cooling device by gas jet for a steel strip, the opening hole position of the gas suction hole group 5 is arranged at the rear part of the opening hole position of the cooling nozzle group 2 so that both gas flow are not largely interferred. That is, each spouting hole in the cooling nozzle group 2 projects by the pipe length L from the opening position of the gas suction hole group 5. The cooling gas spouted from the cooling nozzle 2 straightly reaches the surface of steel strip 1 without scarcely affected by the adjacent gas suction holes 5, and after acting as the cooling medium for the steel strip, the cooling gas is turned over and sucked into the gas suction holes 5. Since a large part of the cooling gas spouted from the cooling nozzle 2 acts as the cooling medium, excellent cooling capacity is displayed. The nearer the interval between the cooling nozzle 2 and the suction hole 5 is, the more remarkable this inclination is.