A sterilization device includes: a flow tube that extends in a longitudinal direction； a housing that extends in the longitudinal direction along the flow tube and surrounds an outer circumference of the flow tube； and a light emitting device provided inside the housing and outside the flow tube and irradiating a fluid flowing in the flow tube with ultraviolet light. An inner surface of the housing is made of a material that reflects the ultraviolet light from the light emitting device, and a shape of a cross section of the inner surface of the housing perpendicular the longitudinal direction is non-analogous to a shape of a cross section of the flow tube perpendicular to the longitudinal direction.
