A medicine syringe having a (i) syringe barrel, (ii) piston and, (iii) plunger rod said syringe barrel being provided with (a) a cylindrical main body defining therein a chamber to be filled with a medical solution, (b) an injection nozzle portion for injecting the medical solution, said injection nozzle portion being formed at an end portion of the main body and defining therein a hollow bore in communication with the chamber, the injection nozzle portion is provided with an injection port for injecting out the medical solution, (c) an opening formed at an opposite end portion of the main body for receiving the piston and plunger, and (d) a flange portion, and said plunger rod being in a form of a rod having the piston arranged at an end portion thereof and a plunger flange formed at an opposite end portion thereof, wherein the chamber in the main body and said hollow bore in the injection nozzle portion have a total capacity of not greater than 0.5 mL, the chamber and hollow bore are formed such that the piston is slidable in a range of from 20 to 100 mm and is allowed to slide liquid-tight into the hollow bore of the injection nozzle portion beyond the chamber located in the main body. characterized in that: - a reduced diameter portion is formed inside of the injection port, and the chamber and hollow bore have the same diameter up to the reduced diameter portion; and - a material of the syringe barrel that makes up the medicine syringe is a synthetic resin. (i) syringe barrel, (ii) piston and, (iii) plunger rod said syringe barrel being provided with (a) a cylindrical main body defining therein a chamber to be filled with a medical solution, (b) an injection nozzle portion for injecting the medical solution, said injection nozzle portion being formed at an end portion of the main body and defining therein a hollow bore in communication with the chamber, the injection nozzle portion is provided with an injection port for injecting out the medical solution, (c) an opening formed at an opposite end portion of the main body for receiving the piston and plunger, and (d) a flange portion, and said plunger rod being in a form of a rod having the piston arranged at an end portion thereof and a plunger flange formed at an opposite end portion thereof, wherein the chamber in the main body and said hollow bore in the injection nozzle portion have a total capacity of not greater than 0.5 mL, the chamber and hollow bore are formed such that the piston is slidable in a range of from 20 to 100 mm and is allowed to slide liquid-tight into the hollow bore of the injection nozzle portion beyond the chamber located in the main body. characterized in that: - a reduced diameter portion is formed inside of the injection port, and the chamber and hollow bore have the same diameter up to the reduced diameter portion; and - a material of the syringe barrel that makes up the medicine syringe is a synthetic resin. (a) a cylindrical main body defining therein a chamber to be filled with a medical solution, (b) an injection nozzle portion for injecting the medical solution, said injection nozzle portion being formed at an end portion of the main body and defining therein a hollow bore in communication with the chamber, the injection nozzle portion is provided with an injection port for injecting out the medical solution, (c) an opening formed at an opposite end portion of the main body for receiving the piston and plunger, and (d) a flange portion, and - a reduced diameter portion is formed inside of the injection port, and the chamber and hollow bore have the same diameter up to the reduced diameter portion; and - a material of the syringe barrel that makes up the medicine syringe is a synthetic resin.