Provided is a filter medium for a liquid filter, having a three-dimensional micropore structure of a multi-layered structure using a multilayer nanofiber web that is obtained by performing air-electrospinning, to thus be thin but have high efficiency and long life, a method of manufacturing the filter medium using the multilayer nanofiber web, and a liquid filter using the filter medium. The filter medium for a liquid filter, includes: a nanofiber web that is made by stacking nanofibers that are obtained by air-electrospinning a fibrous polymer material and that have micropores; and a supporter that is inserted and combined onto one surface or in an inner portion of the nanofiber web.