To improve the sterilizing ability by increasing the irradiation efficiency of ultraviolet light to a fluid flowing through a flow path.SOLUTION: The fluid sterilization apparatus 10 has a first end portion 21 and a second end portion 22 opposite to the first end portion 21, and is provided with a flow path pipe 20, a light source (first light source 50) which is provided in the vicinity of the first end portion 21 and irradiates ultraviolet light in the axial direction from the first end portion 21 toward the treatment flow path 12, a light source And a casing (first casing 30) that partitions the rectifying chamber (first rectifying chamber 13) that surrounds the outer side in the radial direction. The flow regulating chamber has a circulation port (outflow port 37) serving as an inlet or an outlet of the fluid flowing through the processing flow path 12, and includes a first end portion 21, a facing member (a first end portion) 21 facing the first end portion 21 in the axial direction (The first gap 15) between the processing flow path 12 and the processing flow path 12.(FIG.【課題】流路を流れる流体への紫外光の照射効率を高めて殺菌能力を向上させる。【解決手段】流体殺菌装置10は、第1端部21と第1端部21とは反対側の第2端部22とを有し、軸方向に延びる処理流路12を区画する流路管20と、第1端部21の近傍に設けられ、処理流路12に向けて第1端部21から軸方向に紫外光を照射する光源(第1光源50)と、第1端部21の径方向外側を囲う整流室(第1整流室13)を区画する筐体(第1筐体30)と、を備える。整流室は、処理流路12を流れる流体の入口または出口となる流通口(流出口37)を有し、第1端部21と、第1端部21と軸方向に対向する対向部材(第1窓部36)との間の隙間(第1隙間15)を介して処理流路12と連通する。【選択図】図1
