Autoinjector device, elongated along a longitudinal axis A, having a proximal end and an opposing distal end, said device comprising: a syringe having a substantially circular cross section having an outer diameter, said syringe having a proximal end comprising a neck and a distal end provided with a from the outer periphery of the container radially extending flange; said syringe further comprising a movable plunger, a needle and a tubular needle shield having an outer diameter which is larger than the outer diameter of the syringe; an elongated autoinjector housing comprising a space for said syringe; a driving mechanism arranged in the distal end of the housing in order to, when the autoinjector is activated, apply a force on the movable plunger; a syringe holder having a syringe holder wall with a substantially tubular shape, said holder wall having: an open distal end provided with a distal supporting collar arranged around the outer periphery of said syringe holder wall to support said syringe by the radially extending flange, an open proximal end being flexible in a radially outwards direction and provided with a proximal supporting collar arranged around the inner periphery of said syringe holder wall to support said syringe neck, and a slot extending from said open proximal end in the distal direction resulting in a C-shaped cross sectional shape of the syringe holder wall in the proximal end, the outer periphery of the proximal end of the syringe holder is radially supported by one or more contact surfaces on the inside surface of the autoinjector housing when the syringe holder is in a proximal position within the autoinjector, characterised in that the elongated autoinjector housing has a proximal housing section and a distal housing section and the syringe holder is movably arranged in the proximal housing section between a distal position in which the syringe may be inserted and a proximal assembled position. a syringe having a substantially circular cross section having an outer diameter, said syringe having a proximal end comprising a neck and a distal end provided with a from the outer periphery of the container radially extending flange; said syringe further comprising a movable plunger, a needle and a tubular needle shield having an outer diameter which is larger than the outer diameter of the syringe; an elongated autoinjector housing comprising a space for said syringe; a driving mechanism arranged in the distal end of the housing in order to, when the autoinjector is activated, apply a force on the movable plunger; a syringe holder having a syringe holder wall with a substantially tubular shape, said holder wall having: an open distal end provided with a distal supporting collar arranged around the outer periphery of said syringe holder wall to support said syringe by the radially extending flange, an open proximal end being flexible in a radially outwards direction and provided with a proximal supporting collar arranged around the inner periphery of said syringe holder wall to support said syringe neck, and a slot extending from said open proximal end in the distal direction resulting in a C-shaped cross sectional shape of the syringe holder wall in the proximal end, an open distal end provided with a distal supporting collar arranged around the outer periphery of said syringe holder wall to support said syringe by the radially extending flange, an open proximal end being flexible in a radially outwards direction and provided with a proximal supporting collar arranged around the inner periphery of said syringe holder wall to support said syringe neck, and a slot extending from said open proximal end in the distal direction resulting in a C-shaped cross sectional shape of the syringe holder wall in the proximal end, the outer periphery of the proximal end of the syringe holder is radially supported by one or more contact surfaces on the inside surface of the autoinjector housing when the syringe holder is in a proximal position within the autoinjector, characterised in that the elongated autoinjector housing has a proximal housing section and a distal housing section and the syringe holder is movably arranged in the proximal housing section between a distal position in which the syringe may be inserted and a proximal assembled position.