To provide an ultraviolet sterilizing apparatus that is capable of efficiently performing ultraviolet sterilization on a large volume of gas or pressurized liquid in a short time, can be made compact, and can be stably and safely used for a long time.A pressurized fluid sterilizing apparatus including a pressure-resistant container or piping that provides pressurizing space, the pressurized fluid sterilizing apparatus sterilizing pressurized fluid such as pressurized gas and pressurized liquid in the container or piping by irradiating the pressurized fluid with ultraviolet rays, the pressurized fluid sterilizing apparatus being characterized in that the pressurized gas or pressurized liquid in the pressurizing space is irradiated with ultraviolet rays by placing an optical member for ultraviolet emission such as a diffusion lens and a light guide plate in the pressurizing space, transmitting ultraviolet rays emitted from an ultraviolet light source such as an ultraviolet light emitting diode by using a light transmission path such as an optical fiber to the optical member for ultraviolet emission, and emitting the ultraviolet rays.
