A liquid drug-filtering filter medium is provided, which can include a nanofiber web having a three-dimensional network structure for filtering foreign substances included in a liquid drug. According to the embodiment, the occurrence of differential pressure when drawing in and filtering a liquid drug is minimized, and thus the liquid drug may be quickly drawn into a syringe cylinder within a short time and by applying small force, and at the same time, the filtration rate of foreign substances in the liquid drug is very outstanding. A method for producing the liquid drug-filtering filter medium is also provided, which enables the very easy adjustment of a pore structure of the filter medium or the diameters of the pores in order to enable the pore structure to minimize the occurrence of differential pressure or change the differential pressure to a target level.
