The ergonomic protective shell device of the orthosis type includes a structure provided with a front end and a rear end. The structure has a shape widening from the front end to the rear end and is symmetrical along a longitudinal vertical median plane. The structure includes at least one cavity extending from one to the other of the ends. The cavity follows the widening shape and includes a narrowing in the area of the widened rear end. There are rigid support zones formed in the area of the widened rear end on each side of the narrowing of the cavity.
