PURPOSE: To decompose and remove agricultural chemicals and nitrogen by biologically and physically treating waste water contg. agricultural chemicals and nitrogen such as waste water of golf links.

CONSTITUTION: In a first treatment stage for performing treatment of waste water in an aeration state in a first treatment tank 5 packed with an aerobic immobilization carrier 13, BOD, COD and SS are mainly removed by aerobic microorganisms and transparency is enhanced. Then in a second treatment stage for performing treatment of waste water in the aeration state in a second treatment tank 6 packed with a carbonaceous filler 15 previously immobilized with BSK fungi, agricultural chemical components are mainly decomposed by BSK fungi and removed by physical adsorption on the carbonaceous filler 15. Then in a third treatment stage for performing treatment of waste water in the aeration state in a third treatment tank 7 packed with an aerobic and anarobic copresent immobilization carrier 14, denitrification treatment is performed by BSK fungi and the anaerobic microorganisms.