Provided is an apparatus and method for performing tertiary treatment of sewage based on porous filtering media. The apparatus for performing tertiary treatment of sewage based on porous filtering media includes a reaction tank for receiving effluent wastewater from a primary settling tank; and porous filtering media, which is located in the reaction tank and has a predetermined size of surface area and opening, for settling suspension in the effluent wastewater and removing organic matter and nutritive salts included in the suspension.