The present invention relates to a filtering syringe, and more particularly, to an apparatus obtained by improving a syringe provided with a filter means for filtering foreign substances such as glass fragments of an ampoule, so that opening or closing of a one-way valve means is controlled depending on whether a cap is separated, and that the filter means can be also designed to be larger in cross-sectional area so as to allow a liquid medicine to be smoothly sucked with a smaller force. The filtering syringe includes an injection needle 10 comprised of a needle body 11 and a hub 12, and a cylinder 20 to which the injection needle 10 is coupled, preferably, the hub 12 of the injection needle 10 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 formed with through-holes 12e communicating with the cylinder 20； a one-way valve means 300 made of an elastic material and having a cylindrical portion 360 and a wing portion 370 is provided on the inner wall surface 12a, and an end of the wing portion 370 is in elastic contact with the outer wall surface 12b； a filter means 200 is provided within the annular space 12d between the one-way valve means 300 and the though-holes 12e； and the filtering syringe further includes a cap 100 comprised of a hollow body with a sharp tip and hermetically coupled to an outer peripheral surface of the hub 12, wherein an opening/closing means 400 surrounding the needle body 11 is provided within the cap 100. The filtering syringe is configured such that the liquid medicine is filtered and sucked through the filter means having the larger cross-sectional area even with the smaller force in a cap-assembled state and the one-way valve means is automatically closed to allow the liquid medicine to be injected in a cap-separated state, thereby maximizing user's convenience and marketability of the syringe.
