It includes: that shell (11) is positioned to receive syringe that automatic injector (10), which conveys liquid medicine, piston and discharge medicine for syringe, the shell has expection proximally and distally, is using against injection site, wherein syringe includes. The end of injector housing of multiple plunger members (16) between one section and piston, the multiple piston element have longitudinal axis And rope (19) is set as connecting multiple piston elements, wherein piston element, which is configured to become aligned to act on when being proximally displaced to drug rope along their axis promotion piston, passes through driving force.
