Manual injection device comprising a lower body (1) receiving a reservoir (S), said reservoir being mounted such that it is axially movable in said lower body (1) and containing the fluid product to be injected, the reservoir (S) comprising a piston (P) and a needle (A), an upper body (2) mounted such that is axially movable relative to the lower body (1) upon actuation, the upper body (2) having a piston rod (TP) cooperating with the piston (P) during injection to move the latter in the reservoir (S), and a sleeve (10) movably mounted, relative to the lower body (1), between a rest position in which the sleeve (10) is disposed inside the lower body (1), and a projecting position in which said sleeve (10) is moved axially out of the lower body (1), wherein the sleeve (10) is locked in its rest position prior to the actuation of the manual injection device and is automatically urged to its projecting position following the injection, the piston rod (TP) cooperating with the reservoir (S) or with any element rigidly connected to said reservoir (S) to form an injection lock, the force required for axially moving the reservoir (S) in the lower body (1) being less than the force required to trigger the injection lock, such that pricking takes place before the injection is carried out, and wherein, prior to actuation, the piston rod (TP) is connected to a ring (60) which is attached, and in particular crimped, onto a radial flange (9) of the reservoir (S).Dispositif d'injection manuelle comportant un corps inférieur (1) recevant un réservoir (S), ledit réservoir étant monté axialement déplaçable dans ledit corps inférieur (1) et contenant du produit fluide à injecter, ledit réservoir (S) comportant un piston (P) et une aiguille (A), un corps supérieur (2) monté axialement déplaçable par rapport audit corps inférieur (1) lors de l'actionnement, ledit corps supérieur (2) comportant une tige de piston (TP) coopérant avec ledit piston (P) lors de l'injection pour le déplacer
