Disclosed is an apparatus and method for treating wastewater using contact media. The water treatment apparatus includes a biofilm reactor (13) including first and second biofilm contact layers (2 and 3) alternately arranged in a hopper, a precipitator (9) for receiving wastewater from a wastewater collecting tank and purified wastewater from a collecting hopper (4), and precipitating sludge contained in the wastewater, the precipitator (9) being connected with a sludge discharge pipe (8), and a wastewater circulating unit (11) for recycling decant water in the precipitator (9) into the biofilm reactor (13), using a circulating pump (10). By this arrangement, it is possible to achieve a considerable enhancement in wastewater purification efficiency while achieving compactness of the installation because sewage, sanitary sewage, and wastewater can be purified by the alternating biofilm contact layers vertically arranged in pairs to form a multi-stage laminated structure.