To provide a heat treatment gas spraying means and to uniformly spray a heat treatment gas to improve a heat treatment effect by improving heat exchanging efficiency by preventing unevenness in heat treatment by a hollow nozzle.

This rapid heat treatment device includes: a mounting mechanism for mounting a base 34 of a heat treatment gas injection nozzle 30 to a heat treatment gas supply duct 26 in a state that the heat treatment gas injection nozzle is oscillatable in the directions to be close to or separated from a belt face of a conveying belt 12; and an adjusting mechanism 50 having a locking structure 60 lockable to a fixing frame 18 disposed in adjacent to the conveying belt, and a connecting structure connecting the tip 36 of the heat treatment gas injection nozzle 30 and the belt face of the conveying belt 12 in a state that a distance therebetween is adjustable. By adjusting the distance between the tip 36 of the heat treatment gas injection nozzle 30 and the belt face with the fixing mechanism, the distance between the nozzle port 30d of the heat treatment gas injection nozzle 30 and the belt face is unified from the base 34 to the tip 36 of the heat treatment gas injection nozzle 30.