A safe injection device, relating to the field of medical instruments, comprising a needle tube (1), a needle seat (2), an elastic member, a sliding block (4), a needle tip sleeve (5), a protective sleeve (6) and an outer cover (7)； the needle seat (2), the elastic member, the sliding block (4), the needle tip sleeve (5) and the protective sleeve (6) are sequentially sleeved by taking the needle tube (1) as a shaft； and the sliding block (4) is configured to rotate in an irreversible manner after one use. The injection device has a simple and reasonable structure, is safe, telescopic and easy to use, avoiding the fear of a needle tip during injection when in use. After the injection device has been used, by means of the eccentric center principle, a downward pressing stroke is blocked, and the injection device cannot be completely pressed again, and at this time, the needle tip will no longer be exposed, thereby more effectively avoiding the risk of cross infection caused by accidentally touching the needle tip after use； in addition, this structure makes it difficult to return to the original position after use, thus after being used, the injection needle is safer and will not be used again, effectively avoiding cross infection. After the injection device has been used, a warning that the device has been used is given by raising the colored sliding block (4).L'invention concerne un dispositif d'injection sûr, se rapportant au domaine des instruments médicaux, comprenant un tube d'aiguille (1), un support d'aiguille (2), un élément élastique, un bloc coulissant (4), un manchon de pointe d'aiguille (5), un manchon de protection (6) et un couvercle externe (7) ； le support d'aiguille (2), l'élément élastique, le bloc coulissant (4), le manchon de pointe d'aiguille (5) et le manchon de protection (6) sont emmanchés de manière séquentielle en prenant le tube d'aiguille (1) comme corps ； et le bloc coulissant (4) est configuré pour tourner de manière irréversible après u
