The present invention relates to a filter medium for a liquid filter and a method for manufacturing same, capable of forming a thin filtering layer by laminating a light-weight nanofiber web onto a porous non-woven fabric while reducing differential pressure from before and after filtering by reducing the weight of nanofiber content in a unit surface area, thereby increasing the amount of flow passing through. The filter medium according to the present invention comprises: a porous support body for carrying out the role of a strength support body; and the nanofiber web comprising nanofiber, which comprises a polymer substance and is laminated onto one side surface of the porous support body, and has fine pores having a three-dimensional structure through which a liquid to be treated is passed, wherein the content of the nanofiber is less than 5gsm.