The present invention relates to an air sterilizer comprising: a case in which an inlet and an outlet are respectively formed in a lower side and an upper side thereof； a deodorizing filter installed in an upper side of the inlet in the case, and making air fed from the inlet passed therethrough； a reflection duct unit vertically installed in an upper side of the deodorizing filter, providing a path for discharging air passed through the deodorizing filter to an opening formed in an upper end thereof through a suctioning hole formed in a lower end thereof, having a reflection surface formed therein, and having an optical catalyst re-coating unit formed on the reflection surface； a suctioning fan installed in the suctioning hole, and providing ventilation force discharged to the outlet along the inside of the reflection duct unit through the inlet； ultraviolet lamps vertically installed in the reflection duct unit, formed to be disposed in a triangle shape on the circumference of the path, and respectively irradiating ultraviolet rays； an optical catalyst filter installed in an upper side of the reflection duct unit, and making air discharged from the reflection duct unit passed therethrough； and a guide installed in an upper side of the optical catalyst filter, and guiding air passed through the optical catalyst filter. According to the present invention, when air is continuously treated through multiple stages by means of a deodorizing filter, an ultraviolet lamp, an optical catalyst re-coating unit, and an optical catalyst filter, deodorizing, sterilizing, and organic material decomposing effects are excellent. Also, ultraviolet lamps are effectively disposed, so a contaminated air sterilizing effect using ultraviolet rays is maximized. The air sterilizer has a relatively simple structure, so assembling properties and maintenance may be advantageously ensured.본 발명은 하부와 상부에 유입구와 토출구가 각각 형성되는 케이스； 상기 케이스의 내측에서 상기 유입구의 상측에 설치되고, 상기 유입구를 통해 유입되는 공기가 통과하도록 하는 탈취필터； 상기
