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 as to prevent an injection needle or an injection flow passage from being contaminated with the foreign substances while allowing a liquid medicine to be smoothly sucked with a smaller force. The filtering syringe includes an injection needle (10), a cylinder (20) and a plunger and further includes a suction flow passage formed from a liquid medicine-container to the cylinder (20)； an injection flow passage formed from the cylinder (20) to the injection needle (10)； a filter means and a one-way valve means provided in the suction flow passage； and a detachable opening/closing means provided in the injection flow passage, wherein a flow passage portion of the suction flow passage extending from the liquid medicine-container to the filter means is formed independently of an outer peripheral surface of the injection needle (10) and the injection flow passage. The filtering syringe is configured such that the injection needle or the injection flow passage is isolated from the suction flow passage which is upstream of the filter means and in which the foreign substances may remain together with the liquid medicine, and such that the filter means and the one-way valve means responsible for a larger force required when the liquid medicine is sucked are externally provided, thereby allowing the liquid medicine to be sucked with a force less than that required for a conventional syringe and thus maximizing user's convenience and marketability of the syringe.
