US Patent 11396458 Fluid sterilization apparatus

A fluid sterilization apparatus includes: a flow passage tube in which a processing passage where a passing fluid is sterilized is formed; a first light source that irradiates the processing passage with ultraviolet light; an inflow passage formed in a direction that intersects an outer circumferential surface of the flow passage tube; and a communication passage that causes the inflow passage to communicate with the processing passage. The communication passage has a narrow passage in the middle of a path from the inflow passage toward an opening of a first end, the narrow passage being narrower than a passage toward the inflow passage.