Abstract: A filter structure for a syringe comprises a filter unit installed within a cylinder and connected to a needle coupled to the front of the cylinder-in order to perform filtering when an injection solution introduced into the cylinder through the rear thereof is discharged through the needle, wherein a second fluid passage is formed outside a first fluid passage, and the filter unit comprises: a first check valve that is connected with the needle and blocks the second fluid passage; a second check valve that blocks the first fluid passage; a filter member installed on the second fluid passage; and a filter body located between the first check valve and the filter member and coupled to the first check valve at the front thereof and to the second check valve at the rear thereof.

Abstract: Injection liquid is inhaled into a cylinder of a syringe through an injection needle, a passing hole and an inhalation path in order. The liquid in the syringe is injected into a patient's body through a discharge path, a filter and the passing hole in order. The injection occurs a filter holder is rotated at the same time with a movement of a pressure rib along a spiral groove when a needle holder carries out a rectilinear motion.