A sterilization device includes: a reservoir, a supply port, an output port and a light source. The reservoir part includes a first half reservoir part having a substantially hemispherical shape and located on an upstream side in a flow direction of the fluid at the supply port, and a second half reservoir part having a substantially hemispherical shape and located on a downstream side in the flow direction. The supply port opens to the first half reservoir part. The output port opens to the second half reservoir part. When the supply port and the output port are projected on a virtual plane orthogonal to an extending direction of an inner surface of a supply channel connected to the reservoir part at the supply port, a center of gravity of the supply port and a center of gravity of the output port are separated from each other.