A kind of injection device, it comprises: housing is used to hold and has dispensing piston (18) with the content of the syringe syringe (4) by pin (8) discharging Be used for inside elastomeric element (40) away from housing bias voltage syringe and pin First joint element (32) can be towards a described end motion, so that make the needle movement of syringe go out opening and make the end motion of the dispensing piston of syringe towards the surface Thereby can be operated to releasing syringe makes pin inwardly leave the mechanism of housing motion Drive jointer, thereby be used for giving dispensing piston with the Motion Transmission of described first joint element from the dispensing piston that described first joint element extends to syringe, wherein, trigger this mechanism with releasing syringe, and this mechanism is included in the back that is triggered and postponed the composition member of the release of syringe before predetermined period, thereby can guarantee that dispensing piston arrives end surface before releasing syringe.
