PURPOSE: A filamentous fungus inhibitor and a method for controlling filamentous fungi in waste water using the same are provided to easily and continuously purify industrial waste water. CONSTITUTION: A filamentous fungus inhibitor contains A agent containing ammonium bicarbonate which is uniformly dispersed in zeolite, and B agent containing ferrous sulphate which is uniformly dispersed in zeolite. A method for controlling filamentous fungi in waste water comprises: a step of adding 40-100ppm of each A agent and B agent to the waste water； and a step of performing aeration of the waste water. The method comprises a step of maintaining dissolved oxygen (DO) to 1ppm or more by aeration before adding A agent and B agent. The method also comprises a step of treating the waste water with acid or alkali to adjust pH to 5.0-5.5 before adding A agent and B agent.본 발명은 중탄산암모늄을 제올라이트에 균질하게 담지한 A제와, 황산제1철을 제올라이트에 균질하게 담지하여 B제로 이루어진 사상균 억제제 및 이를 이용한 폐수 중의 사상균 제어 방법을 개시한다.
