A safe auto-needle device for injection, comprising: a) a main housing (210, 310, 410); b) a syringe-support (260, 360, 460, 860) 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 (226, 426) terminating in a needle; said needle covered by a needle sheath; c) a drive mechanism for advancing said syringe-support (260, 360, 460, 860) distally towards an injection site; d) a generally tubular needle shield (220, 320, 420) concentric to said main housing (210, 310, 410); said needle shield (220, 320, 420) 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 (220, 320, 420) comprising a distal end (226, 426) for contacting an injection site, and a proximal end; e) a spring urging distal movement of said needle shield (220, 320, 420); and said needle shield (220, 320, 420) comprising a spring seat; f) a needle sheath remover (240, 340), designed to mate with and irreversibly grip said needle sheath, for removal of said needle sheath 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 (226, 426) of said generally tubular needle shield (220, 320, 420), results in release of said locking mechanism; and said tubular needle shield (220, 320, 420) cannot be depressed prior to removal of said needle sheath; h) a plunger rod (290, 390) 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 (240, 340) is grasped and removed; said distal end (226, 426) of said needle shield (220, 320, 420) 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 (260, 360, 460, 860) and said associated syringe, distally until needle penetration; and upon depressing of said plunger, a medicament may be injected. a) a main housing (210, 310, 410); b) a syringe-support (260, 360, 460, 860) 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 (226, 426) terminating in a needle; said needle covered by a needle sheath; c) a drive mechanism for advancing said syringe-support (260, 360, 460, 860) distally towards an injection site; d) a generally tubular needle shield (220, 320, 420) concentric to said main housing (210, 310, 410); said needle shield (220, 320, 420) 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 (220, 320, 420) comprising a distal end (226, 426) for contacting an injection site, and a proximal end; e) a spring urging distal movement of said needle shield (220, 320, 420); and said needle shield (220, 320, 420) comprising a spring seat; f) a needle sheath remover (240, 340), designed to mate with and irreversibly grip said needle sheath, for removal of said needle sheath 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 (226, 426) of said generally tubular needle shield (220, 320, 420), results in release of said locking mechanism; and said tubular needle shield (220, 320, 420) cannot be depressed prior to removal of said needle sheath; h) a plunger rod (290, 390) 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 (240, 340) is grasped and removed; said distal end (226, 426) of said needle shield (220, 320, 420) 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 (260, 360, 460, 860) and said associated syringe, distally until needle penetration; and upon depressing of said plunger, a medicament may be injected.