PROBLEM TO BE SOLVED: To maintain sterilization performance. The fluid sterilizer of the embodiment includes a processing chamber, a light source chamber, a partition member, and a first film. The processing chamber processes the fluid. In the light source room, a light source that irradiates ultraviolet rays toward the processing room is installed. The partition member has ultraviolet transmission and separates the processing chamber and the light source chamber. The first film covers the first surface of the partition member facing the processing chamber. [Selection diagram] Fig. 2【課題】殺菌性能を維持する。【解決手段】実施形態の流体殺菌装置は、処理室と、光源室と、仕切部材と、第１膜とを具備する。処理室は、流体を処理する。光源室は、処理室に向けて紫外線を照射する光源が設置される。仕切部材は、紫外線透過性を有し、処理室と光源室とを区画する。第１膜は、処理室に対向する仕切部材の第１面を覆う。【選択図】図２
