The invention concerns a device for back injecting an implant (30) into the skin (22) of a subject, said device (1) include a hollow main body (10), to which a hollow needle (28) is fixed into which the implant (30) is introduced, a secondary body (12; 114) coaxially arranged inside the main body (10) and surrounding the needle (28) and a piston rod (88) able to slide coaxially inside said hollow needle (28) and whose position relative to said needle (28) remains unchanged when the back injection device (1) is pressed against the subject's skin (22) to allow the needle (28) to penetrate said subject's skin and when the secondary body (12) retracts inside the main body (10), the piston rod (88) penetrating the interior of the hollow needle (28) to hold the implant (30) at the required depth in the subject's skin (22) during withdrawal of the hollow needle (28) from the subject's skin (22), during which the secondary body (12; 114) exits the main body (10), characterized in that it includes means for the elastic return of the secondary body (12) from the main body (10).