A kind of needle guard mechanisms being injected intravenously remaining needle are the needle point that a syringe needle is stored with what, include plastic body and an at least metal clips. Plastic body, center have a through hole worn for syringe needle, and by being extended at least a positioning groove along plastic body outer rim centered on through hole； Metal clips system sets in the locating slot of what plastic body, and metal clips system extends along the through hole path of plastic body, and in part metals elastic slice exposure what through hole, is contacted generation deformation by the tube wall of syringe needle. It uses, when syringe needle is extracted outward, a notch is equipped with by what syringe needle, when notch is moved to the position of metal clips, using the deformation of metal clips, and then in the notch of fastening what syringe needle, make needle point by the fixation what plastic body of safety.一種靜脈注射留置針之針頭保護裝置，係用於收納一針頭之針尖，包含塑膠本體以及至少一金屬彈片。塑膠本體，其中心具有一可供針頭穿設之貫穿孔，且由貫穿孔為中心沿塑膠本體外緣延伸有至少一定位槽；金屬彈片係設於塑膠本體之定位槽內，金屬彈片係沿塑膠本體之貫穿孔路徑延伸，且部分金屬彈片暴露於貫穿孔中，受針頭之管壁頂觸產生形變。藉以，當針頭向外拔出時，由於針頭上設有一缺口，當缺口移動至金屬彈片之位置時，利用金屬彈片之形變，進而扣合於針頭之缺口中，使針尖被安全的固定於塑膠本體內。
