A fluid sterilization device 10 includes: a housing 12 that defines a flow passage 13 extending in a longitudinal direction； a filter 40 provided in the housing 12 and extending in the longitudinal direction； and a light source 50 including a light emitting device 52 that emits ultraviolet light and irradiating a fluid passing through the filter 40 and flowing in a laminar flow state with the ultraviolet light. The filter 40 may be a hollow fiber filter. The light source 50 may be provided to radiate ultraviolet light in the longitudinal direction.
