A single use syringe mainly comprises a plunger arm, a plunger tip, a syringe body, and a tip retaining sleeve. The tip retaining sleeve is surroundingly disposed to a circumference of a tip retaining arm of the plunger tip in order to have the tip retaining arm engaged to the plunger arm. When a user pull back the plunger arm, sleeve rib on the tip retaining sleeve is locked to the syringe body, so as to limit the tip retaining sleeve from being pushed forward again. Under this condition, if a user presses the plunger arm, the tip retaining arm starts to disengage from a fitting range of the tip retaining sleeve making the plunger arm and the plunger tip separated from each other. After the plunger arm and the plunger tip are separated from each other, the plunger arm and the plunger tip can not be re-engaged again. Accordingly, the single use syringe can achieve the objective of not being reused.一種一次性注射器,其主要包含有一活塞臂、一活塞端、一注射器本體以及一固定套筒。固定套筒係環繞設置於活塞端的突出尖端之周圍,藉此使得突出尖端卡合於活塞臂。當一使用者回拉活塞臂時,固定套筒上的套筒凸肋將卡掣於注射器本體,藉此限制固定套筒再次被往前推動。此時,若使用者推壓活塞臂,則突出尖端將開始脫離固定套筒的套設範圍,以使得活塞臂與活塞端二者分離。當活塞臂與活塞端分離之後,活塞臂與活塞端將無法再次卡合,藉此,此種一次性注射器達到無法被重複使用之目的。10‧‧‧一次性注射器110‧‧‧手持部120‧‧‧連接柄200‧‧‧固定套筒300‧‧‧活塞端330‧‧‧突出尖端
