The present invention relates to a syringe and, particularly, to a device for more smoothly suctioning a medicinal fluid by sharing a part of an injection channel excluding a syringe needle, or by forming a suction channel completely independent from the injection channel in a conventional syringe having the injection channel including the syringe needle, the syringe comprising a syringe needle (10) and cylinder (20) so as to have an injection channel extending from the cylinder (20) to the syringe needle (10), and further comprising: an opening/closing means (400) for selectively sealing the injection channel； a suction channel including a through-hole (200) for allowing for communication between the inside and the outside of any one of the syringe needle (10), a connector for connecting the syringe needle (10) to the cylinder (20), and the cylinder (20), such that the suction channel extends up to the cylinder (20) from a hollow cap (100) having a tip； and a valve means (300) for controlling the opening and the closing of the suction channel by a user operation. The hollow cap (100) accommodates the opening/closing means (400) and part of the suction flow passage is formed between the interior of the cap (100) and the outer periphery of the opening/closing means (400). Therefore, since a separate suction channel not passing through a syringe needle is formed in a conventional syringe so as to allow a medicinal fluid to suction more smoothly, user convenience and marketability of a product can be maximized, and the suction channel can be forcibly closed during injection. Furthermore, the adhesive material interface (13) between the needle (10) and the needle hub (12) is accommodated in the opening closing means (400) which prevents contamination of the liquid medicine and degradation of the adhesive.
