The present invention relates to a filter syringe and, more specifically, to a device for smoothly sucking a chemical solution with less force, which improves a syringe provided with a filter means for filtering foreign substances such as glass pieces of an ampoule, to thereby control the opening and closing of a one-way valve means depending on whether a cap is detached or not while the sectional area of the filter means can be designed to be wide. A syringe includes: a needle (10) consisting of a tip of a needle (11) and a hub (12)； and a cylinder (20) connected to the needle (10), wherein the hub (12) is formed with an annular space (12d) having an inner wall surface (12a), an outer wall surface (12b) and a bottom surface (12c), and the bottom surface (12c) is provided with a through hole (12e) formed to be connected to the cylinder (20)； a one-way opening and closing means (300) of elastic material having a cylindrical part (360) and a wing part (370) is provided on the inner wall surface (12a), and an end of the wing part (370) elastically contacts the outer wall surface (12b)； a filter means (200) is provided in the annular space (12d) between the one-way opening and closing means (300) and the through-hole (12e)； and further provided is a cap (100) which has therein an opening and closing means (400) for surrounding the needle (11) and which comprises a hollow body having a sharp end to be hermetically sealed and coupled to the outer circumferential surface of the hub (12), such that in a state where the cap is assembled, a chemical solution is filtered and sucked through a filter means having a wide cross-sectional area with less force, and the one-way valve means is closed by itself and the chemical solution is injected in a state where the cap is separated, thereby maximizing convenience for a user and the commerciality of a syringe.
