A plastic-made nozzle cap for a plastic syringe includes a leg section, a cavity top wall portion, and a finger knob for the attachment/detachment of the nozzle cap. The leg section is structured for connection with a female Luer lock fitting formed face-to-face with an outer circumferential wall of a syringe nozzle. The cavity top wall portion is provided with a curved surface having a downwardly-convex, radius of curvature ranging from 0.6 to 12.0 mm for being brought into contact with a tip of the syringe nozzle to maintain sealing performance. The finger knob is arranged on an upper side of the leg section, and extends above the female Luer lock fitting in a state that a syringe barrel and the nozzle cap have been connected together.
