Patent ID: 8403834

Claim:
An automatic return syringe comprising: a cylindrical body in which a plurality of space portions divided by a partition portion are formed and a syringe port is provided in each of the plurality of space portions; a piston body, which is a piston reciprocally moving in the plurality of space portions in the cylindrical body and has a pusher portion at a rear end, having a plurality of ventilation paths formed through which each of the plurality of space portions communicates with each of a plurality of ventilation holes provided in the pusher portion; and a spring arranged between the piston body and the cylindrical body, for returning the piston body subjected to a pushing operation to an original position the plurality of space portions are arranged in series by laterally dividing the inside of the cylindrical body and the syringe port is provided on a side face of the cylindrical body in the space portion other than the distal-end space portion; and the piston body is provided with a piston portion reciprocally moving in close contact with an inner circumference of the plurality of space portions in the cylindrical body and a shaft portion supporting the piston portion and having an outer diameter smaller than an inner diameter of the cylindrical body, wherein an air supply or suctioning is performed independently from each syringe port.