A safe auto-needle device for injection, comprising: a) a main housing ; b) a syringe-support for receiving a proximal end of a disposable prefilled syringe ; said disposable prefilled syringe comprises: a piston ; a proximal end including a flange ; and a distal end terminating in a needle ; said needle covered by a needle sheath (NS); c) a drive mechanism for advancing said syringe-support distally towards an injection site ; d) a generally tubular needle shield concentric to said main housing ; said needle shield moveable from a first position wherein said needle is covered, to a second position in which said needle is at least partially exposed, to a third fully extended position in which said needle is irreversibly concealed; said generally tubular needle shield comprising a distal end for contacting an injection site , and a proximal end; e) a spring urging distal movement of said needle shield ; and said needle shield comprising a spring seat ; f) a needle sheath (NS) remover , designed to mate with and irreversibly grip said needle sheath (NS), for removal of said needle sheath (BS) prior to injection; g) a locking mechanism for preventing premature advancement of said needle ; wherein said locking mechanism is constructed such that depressing upon said distal end of said generally tubular needle shield , results in release of said locking mechanism; and said tubular needle shield cannot be depressed prior to removal of said needle sheath (NS); h) a plunger rod for engaging said piston of said prefilled syringe , wherein the speed of depressing of said plunger is manually controllable by a user; wherein in use of said device, said NS remover is grasped and removed; said distal end of said needle shield is brought into contact with and pressed upon an injection site , resulting in release of said locking mechanism, and in drive of said syringe-support and said associated syringe, distally until needle penetration; and upon depressing of said plunger, a medicament may be injected. a) a main housing ; b) a syringe-support for receiving a proximal end of a disposable prefilled syringe ; said disposable prefilled syringe comprises: a piston ; a proximal end including a flange ; and a distal end terminating in a needle ; said needle covered by a needle sheath (NS); c) a drive mechanism for advancing said syringe-support distally towards an injection site ; d) a generally tubular needle shield concentric to said main housing ; said needle shield moveable from a first position wherein said needle is covered, to a second position in which said needle is at least partially exposed, to a third fully extended position in which said needle is irreversibly concealed; said generally tubular needle shield comprising a distal end for contacting an injection site , and a proximal end; e) a spring urging distal movement of said needle shield ; and said needle shield comprising a spring seat ; f) a needle sheath (NS) remover , designed to mate with and irreversibly grip said needle sheath (NS), for removal of said needle sheath (BS) prior to injection; g) a locking mechanism for preventing premature advancement of said needle ; wherein said locking mechanism is constructed such that depressing upon said distal end of said generally tubular needle shield , results in release of said locking mechanism; and said tubular needle shield cannot be depressed prior to removal of said needle sheath (NS); h) a plunger rod for engaging said piston of said prefilled syringe , wherein the speed of depressing of said plunger is manually controllable by a user; wherein in use of said device, said NS remover is grasped and removed; said distal end of said needle shield is brought into contact with and pressed upon an injection site , resulting in release of said locking mechanism, and in drive of said syringe-support and said associated syringe, distally until needle penetration; and upon depressing of said plunger, a medicament may be injected. <EOS>