Training device for training a user in the operation of a self-injector that dispenses a medication, the training device comprising: a housing (12) having a distal end (12a) and a proximal end (12b)； a needle guard (30) slidably housed with the distal end (12a) of the housing (12), the needle guard (30) slidable from a first extended position relative to the housing (12) before operation of the training device, to a retracted position with respect to the housing (18) during operation of the training device, and to a second extended position with respect to the housing (18) after operation of the training device； a drive assembly coupled to the needle guard (30), the drive assembly having an elastic element (32) and a lock (34), the drive assembly controlling the movement of the needle guard (30) from the position retracted to the second extended position, blocking the lock (34) to the needle guard (30) in the second extended position in a locked position； and a security element (44) near the proximal end (12b) of the housing (18), characterized in that the security element (44) prevents the movement of the needle guard (30) from the first extended position to the retracted position in a storage position, the needle guard (30) can move towards the retracted position with the security element (44) in the armed position, and the security element (44) resets the lock (34) when returning the safety element (44) to the storage position.Dispositivo de entrenamiento para entrenar a un usuario en el funcionamiento de un auto-inyector que dispensa un medicamento, comprendiendo el dispositivo de entrenamiento: una carcasa (12) que tiene un extremo distal (12a) y un extremo proximal (12b)； un protector de aguja (30) alojado de manera deslizante con el extremo distal (12a) de la carcasa (12), el protector de la aguja (30) deslizable desde una primera posición extendida respecto a la carcasa (12) antes del funcionamiento del dispositivo de entrenamiento, hasta una posición retraí
