A sterilization apparatus (100) is provided with: a housing (10), which forms a flow passage through which a fluid subject to sterilization passes； a light receiving unit (16), which receives a portion of the ultraviolet light emitted from a light source (14) and detects the amount of ultraviolet light that has been received； and a control unit (18), which controls the output of the semiconductor light-emitting element based on information regarding the amount of ultraviolet light acquired from the light receiving unit. The housing (10) has an incidence portion (20) on which ultraviolet light becomes incident and a reflection portion (22), which reflects the ultraviolet light at the inner surface thereof. The light receiving unit (16) is provided at a position where the light receiving unit (16) can receive the portion of ultraviolet light that has been transmitted through the reflection portion (22).
