Provided is a dental syringe that enables easy discharge of air within a syringe body 1 to the exterior while injecting dental material into the syringe body 1 from a discharge port 1a of the syringe body 1 and easy discharge of the dental material that has been injected into the syringe body 1 during use for treatment. A dental syringe includes a syringe body 1, a plunger 2, and an O-ring 3 to be mounted in an engagement groove 2a formed along a circumferential direction of a front end portion of the plunger 2. The engagement groove 2a includes a shallow groove 2aa at the front end side and a deep groove 2ab at the rear end side. The shallow groove 2aa is arranged such that when dental material starts being injected into the syringe body 1, the O-ring 3 restricts movement of the plunger 2 within the syringe body 1, and after air is discharged toward the rear end side of the syringe body 1, the O-ring 3 is held in contact with the inner face of the syringe body 1 with a strength that allows the plunger 2 to be pushed and moved along with the O-ring 3 toward the rear end side by the dental material injected from the discharge port 1a of the syringe body 1. When an end portion at the rear end side of the plunger 2 is pushed by a finger to discharge the dental material, the O-ring is moved from the shallow groove to the deep groove.
