The liquid product injection device is adapted to receive an injection syringe comprising a syringe body, carrying an injection needle, and a piston slidably mounted axially in the syringe body in the distal direction when an injection is performed. The injection device comprises a piston control member intended to cooperate axially, under the effect of an elastic force, with a piston rod, kinematically connected to the piston to slide it. The injection device further comprises at least one slowing member, this slowing member being kinematically connected in its translational movement along the injection axis X to the piston control member, the slowing member being movably mounted in a positioning control member (20) with which it cooperates by slow-cam cam slow-down contact (102, 104), slowing cam and slowing cam path (102, 104) being carried one by the retarding member and the other by the positioning control member (20), the slowing cam path (102, 104) comprising a so-called injection portion (102D, 104D) such that when the retarding cam travels through this injection portion, the piston control member slides the piston, the injection portion (102D, 104D) of the slowing cam path (102, 104) having at least two sections called resp ectively fast (102R, 104R) and slow (102L, 104L), of different inclinations. Le dispositif d'injection de produit liquide est destiné à recevoir une seringue d'injection comprenant un corps de seringue, portant une aiguille d'injection, et un piston monté coulissant axialement dans le corps de seringue dans le sens distal lorsqu'une injection est réalisée. Le dispositif d'injection comprend un organe de commande de piston destiné à coopérer axialement, sous l'effet d'une force élastique, avec une tige de piston, liée cinématiquement au piston pour le faire coulisser. Le dispositif d'injection comprend en outre au moins un organe de ralentissement, cet organe de ralentissement étant lié cinématiquement dans son mouvement de trans
