A fluid sterilization module includes an inner cylinder forming a processing flow path, a case portion in which the inner cylinder is accommodated, a member provided between an outer circumferential surface of the inner cylinder and an inner circumferential surface the case portion, a first chamber located in a region on a side of one end portion of the inner cylinder with respect to the member, in a gap between the inner cylinder and the case portion, a second chamber located in a region on a side of the other end portion of the inner cylinder with respect to the member, and a light emitting element provided in at least one of the one end portion and the other end portion of the inner cylinder, and configured to emit ultraviolet light to the object passing through the processing flow path.