A fluid sterilization device 100 is provided with a light source 14 having a semiconductor light-emitting element 12 for emitting ultraviolet rays, a housing 10 for forming a fluid path through which a fluid as a sterilization object passes, a light receiving part 16 for receiving a portion of the ultraviolet rays emitted from the light source 14 and detecting the intensity of the received ultraviolet rays, and a control part 18 for controlling the output of the semiconductor light-emitting element on the basis of information of the intensity of the ultraviolet rays acquired from the light receiving part. The housing 10 has an incidence part 20 on which the ultraviolet rays are incident, and a reflection part 22 for reflecting the ultraviolet rays on an inside surface thereof. The reflection part 22 is configured from a material for transmitting a portion of the ultraviolet rays, and the light receiving part 16 is provided in a position at which a portion of the ultraviolet rays transmitted through the reflection part 22 can be received.本發明提供一種流體殺菌裝置(100)，具備：光源(14)，其具有射出紫外線的半導體發光元件(12)；框體(10)，用以形成可供作為殺菌對象的流體通過的流路；受光部(16)，用以受光從光源(14)所射出的紫外線的一部分，且檢測所受光的紫外線的光量；以及控制部(18)，其基於從受光部所取得的紫外線光量的資訊來控制半導體發光元件的輸出。框體(10)係具有可供紫外線入射的入射部(20)、以及將紫外線在內面進行反射的反射部(22)。反射部(22)係由使紫外線的一部分穿透的材料所構成；受光部(16)係設置於可以受光已穿透反射部(22)的一部分紫外線的位置。
