The invention provides an optical irradiation equipment and an optical irradiation method by means of which an irradiation with UV rays can be performed while an increase of the temperature of the object to be treated is suppressed. The optical irradiation equipment provided with a cage body having an UV radiation transmission window, and an excimer lamp which is arranged in an interior of said cage body, characterized in that: gas flow openings being connected to one of a cooling gas supply mechanism and a cooling gas suction mechanism are provided at a periphery of said UV radiation transmission window. The excimer lamp has a discharge vessel with an overall shape of a flat plate, a high-voltage side electrode being arranged at one face of this discharge vessel, and an earth-side electrode being arranged at another face of said discharge vessel, wherein the face of said discharge vessel at which said high-voltage side electrode is arranged is positioned opposite to said UV radiation transmission window.