The invention relates to a needle protection device for a pre-filled syringe with staked needle. This device comprises a blocking mechanism, comprising means for fastening to a syringe body, a needle shield, into which the needle can be driven, and an after-use safety system comprising a sleeve defining a central axis along which it is movable and means for resiliently loading the sleeve in a forward position in which it is able to cover the needle. The sleeve comprises an outer tube and a coaxial inner tube that are manufactured in one piece by injection molding, while the outer tube is arranged so as to cooperate with the blocking mechanism, and the inner tube is detachable from the outer tube and axially connected in translation with the needle shield.
