A syringe has a syringe main body, a syringe unit, and a piston. An end surface of the piston disposed on a forward end side is brought in contact with an end surface of a plunger disposed on a proximal end side so that the plunger is slidable toward a discharge port in a state in which a rod portion is accommodated in an accommodating hole in an attached state. In the attached state, the syringe unit is attached to the syringe main body, and a position of the plunger in a charging chamber is determined at a predetermined position at which an amount of an injection objective substance in the charging chamber is a predetermined amount on the basis of a position of the piston arranged in a through-hole of the syringe main body. Accordingly, the syringe is easily handled and the injection objective substance can be correctly charged.
