Safety injection needle device for delivery of a medicament from a storage reservoir with longitudinal axis A, said device comprising: a device body comprising securing means intended for securing the safety injection needle device to the storage reservoir, a sleeve element extending substantially co-axially to axis A in opposite direction to the securing means for the storage reservoir and having an open forward end, and a needle hub arranged within the sleeve element and extending substantially co-axially to axis A; a needle secured in the needle hub and extending co-axially to axis A, said needle comprising a rear end extending from the device body and intended to be arranged within the storage reservoir once the safety injection needle device is secured to the storage reservoir, and a forward end extending from the needle hub past the sleeve element of the device body; a needle shield device with a forward and rear end movably arranged along axis A within the sleeve element between a retracted position where the tip of the needle is exposed outside de forward end, and an extracted position where the tip of the needle is enclosed by the needle shield device, and a spring arranged to resiliently support the needle shield device such that the needle shield device is forced towards the extracted position, characterized in that the needle hub has a substantially circular cross sectional shape transverse to axis A with a smaller radius towards the outer end of the needle hub, and the rear end of the needle shield device is made of a deformable material such that, during movement from the extracted position to the retracted position, at least a section of the rear end of the needle shield device is irreversibly deformed by the needle hub such that the distance from axis A to the irreversibly deformed section of the rear end in radial direction from axis A is increased, and wherein a least one shoulder is formed on the inside wall of the sleeve element such that, after at least a section of the rear end of the needle shield device is irreversibly deformed and the needle shield device is returned to the extracted position, the deformed section of the rear end of the needle shield device will rest against the shoulder and lock the needle shield device in the extracted position. a device body comprising securing means intended for securing the safety injection needle device to the storage reservoir, a sleeve element extending substantially co-axially to axis A in opposite direction to the securing means for the storage reservoir and having an open forward end, and a needle hub arranged within the sleeve element and extending substantially co-axially to axis A; a needle secured in the needle hub and extending co-axially to axis A, said needle comprising a rear end extending from the device body and intended to be arranged within the storage reservoir once the safety injection needle device is secured to the storage reservoir, and a forward end extending from the needle hub past the sleeve element of the device body; a needle shield device with a forward and rear end movably arranged along axis A within the sleeve element between a retracted position where the tip of the needle is exposed outside de forward end, and an extracted position where the tip of the needle is enclosed by the needle shield device, and a spring arranged to resiliently support the needle shield device such that the needle shield device is forced towards the extracted position, characterized in that the needle hub has a substantially circular cross sectional shape transverse to axis A with a smaller radius towards the outer end of the needle hub, and the rear end of the needle shield device is made of a deformable material such that, during movement from the extracted position to the retracted position, at least a section of the rear end of the needle shield device is irreversibly deformed by the needle hub such that the distance from axis A to the irreversibly deformed section of the rear end in radial direction from axis A is increased, and wherein a least one shoulder is formed on the inside wall of the sleeve element such that, after at least a section of the rear end of the needle shield device is irreversibly deformed and the needle shield device is returned to the extracted position, the deformed section of the rear end of the needle shield device will rest against the shoulder and lock the needle shield device in the extracted position.