Antitheft device and antitheft device module for a steering column of a motor vehicle

The invention relates to an antitheft device for a steering column of a motor vehicle destined to comprises a lock (3; 103) that can be operated in rotation by a key (13), said antitheft device comprises: - a locking assembly (4) engaging in a cavity (8) of a steeling column (9) in a locked position to prevent the steering column (9) from rotating, the locking assembly (4) being configured to be operated by the rotation of the lock (3; 103) between the locked position and an unlocked position, - a key sensor (5; 105) cooperating with a key (13) engaged in the lock (3; 103) and cooperating with the locking assembly (4) to prevent the release of the locking assembly (4) when a key (13) is engaged in the lock (3; 103), wherein the locking assembly (4) further cooperates with the key sensor (5; 105) to prevent the disengagement of the key (13) from the lock (3; 103) when the locking assembly (4) is in an unlocked position. This invention also relates to an associated antitheft device module.