Syringe

A syringe for injecting an injection objective substance into an injection target area, the syringe comprising:

• a syringe main body having a through-hole formed in an axial direction;
• a piston slidable in the through-hole;
• a syringe unit comprising a charging chamber configured to accommodate the injection objective substance, a plunger slidable in the charging chamber, and a nozzle portion including a flow passage having an inner diameter smaller than that of the charging chamber, the flow passage allowing the injection objective substance contained in the charging chamber pressurized by sliding movement of the plunger to flow therethrough, the nozzle portion configured to discharge the injection objective substance from a discharge port formed at a forward end of the flow passage, the syringe unit being detachably attached to a forward end side of the syringe main body, the charging chamber configured to receive a first amount of the injection objective substance before the syringe unit is attached to the syringe main body, the plunger configured to move toward the discharge port to define a second amount of the injection objective substance after the syringe unit is attached to the syringe main body and before the injection objective substance is injected into the injection target area;
• and
• a driving unit comprising an ignition device configured to combust powder, the driving unit configured to apply, via the piston to the plunger, discharge energy for discharging the second amount of the injection objective substance from the nozzle portion by the aid of a combustion product produced by the ignition device, wherein:
• the plunger has a rod portion extending toward the piston arranged in the through-hole of the syringe main body from an end surface disposed on a proximal end side in an attached state in which the syringe unit is attached to the syringe main body, the rod portion has an end disposed on the proximal end side;
• the rod portion of the plunger is configured to be inserted into the piston in the attached state such that the end of the rod portion is accommodated without making contact with the piston;
• and
• an end surface of the piston disposed on the forward end side is configured to contact the end surface of the plunger disposed on the proximal end side so that the plunger is slidable toward the discharge port in a state in Which the rod portion is accommodated in an accommodating hole in the attached state,
• wherein the first amount is larger than the second amount, and wherein the syringe unit is configured to discharge a portion of the first amount of the injection objective substance by the movement of the plunger toward the discharge port before the powder combustion such that an amount of the injection objective substance to be injected into the injection target area is the same as the second amount.