A filter needle for a syringe including a syringe needle having a needle, a fixing member for fixing the needle and an inner space formed in the fixing member, and a syringe body having a cylinder, a piston and a front end separably installed in the inner space of the fixing member of the syringe needle, is provided. The filter needle includes a filter structure installed in the inner space of the fixing member of the syringe needle and including an one-way inlet path having an inlet and an one-way outlet path having an outlet, each of which has a check valve function, and a filter installed in the outlet path at a rear end of the outlet to filter a foreign substance, which is input through the inlet together with a medicament liquid, from the medicament liquid such that the medicament liquid is only injected into a patient through the outlet when injecting the medicament liquid into the patient.
