A syringe system includes a syringe and a pressurization device for a syringe. The pressurization device for a syringe is configured so that the plunger advances by a forward rotation of the plunger, and the plunger retracts by a reverse rotation of the plunger. The plunger is advanceable by pressing the gasket at the time of the forward rotation and is retractable with respect to the barrel without pulling the gasket in the proximal end direction at the time of the reverse rotation.