A syringe protecting device equipped with an outer cylinder 4, an inner cylinder 1 and a spring 3, wherein, when the spring 3 is released from its compressed state, the inner cylinder 1 is moved rearward with respect to the outer cylinder 4 so that a syringe needle 202 is stored inside the outer cylinder 4, and the syringe protecting device further equipped with a releasable pre-locking mechanism for fixing the inner cylinder 1 to the outer cylinder 4 while maintaining the spring 3 in the compressed state in the front-rear direction, wherein, the pre-locking mechanism fixes the inner cylinder 1 before movement to the outer cylinder 4 by engaging the protruding sections 22 of the ring 2 with the engaging sections of the through groove sections 42.
