Abstract: A wastewater treatment apparatus for removing nitrogen and phosphorus contained in wastewater, and a method therefor. The wastewater treatment apparatus includes an anaerobic/anoxic reaction tank having multiple compartments partitioned by a plurality of partitions, each compartment receiving wastewater and a carbon source; an aeration tank for removing phosphorus by luxury uptake of phosphorus from the treated wastewater flowed from the last compartment of the anaerobic/anoxic reaction tank, using oxygen as an electron acceptor; and a settling tank for settling a sludge from the treated wastewater passed from the aeration tank, and returning the settled sludge into the anaerobic/anoxic reaction tank. The wastewater treatment apparatus can increase removal efficiencies of nitrogen and phosphorus contained in the wastewater, even at a low temperature. Also, the retention time in the reaction tank is reduced, so the size of the reaction tank is reduced, thereby lowering construction costs.