Abstract: An adapter device (10) is used in order to allow a projectile (12), such as missile, to be launched from a standard launching tube (14), without having to modify the latter. This device comprises an adapter tube (24) in which the projectile (12) is placed, a retaining ring (22) which is mounted on the end of the launching tube (14) and a hooking system (26) for securing the adapter tube (24) to the launching tube. The adapter tube (24) has a front portion (38) provided with grooves for guiding the folded fins of the projectile (12) and a rear portion provided with a bottom onto which is fixed a pulley (36) for returning an optical fiber (20) used for guiding the projectile (12).