A needle protecting module of an injection device in connecting with a syringe has a needle base, a needle body a tube module, a mounting tube, an elastic unit, and a stopping unit. The syringe has a tube body and an axis. The needle body transfixes the needle base and communicates with the tube body for medication injection. The needle base is removably engaged with the tube body and bearing the needle protecting module is transfixed by the needle body. The tube module is mounted around the needle base and has an annular space. The mounting tube is movably inserted into the annular space. The elastic unit is mounted in the annular space and abuts both the mounting tube and the needle base bilaterally. The stopping unit is moveably mounted in the annular space and is selectively engaged with the mounting tube.