The present invention relates to a syringe, and more particularly, to an apparatus obtained by improving a conventional syringe formed with an injection flow passage including an injection needle, so as to share a portion of the injection flow passage except the injection needle or to form a suction flow passage completely independent of the injection flow passage, thereby further smoothing suction of a liquid medicine. The syringe includes an injection needle (10) and a cylinder (20) and is formed with an injection flow passage formed from the cylinder (20) to the injection needle (10). The syringe further includes an opening/closing means (400) for selectively opening or closing the injection flow passage； and a suction flow passage formed from a pointed hollow cap (100) to the cylinder (20) and provided with a through-hole formed in any one of the injection needle (10), a connector (500) for connecting the injection needle (10) to the cylinder (20), and the cylinder (20) to establish communication between an inside and an outside thereof and a one-way valve means (300) for intermittently controlling opening or closing of the through-hole. The syringe is configured such that the separate suction flow passage bypassing the injection needle is formed in a conventional syringe to more smoothly perform the suction of the liquid medicine.
