An air cleaner comprising: a housing (10, 20) including a suction portion configured to suction air from an outside of the housing (10, 20) and a discharge portion configured to discharge air from the housing (10, 20); a frame (100, 200) disposed inside the housing (10, 20); a sterilizer disposed inside the frame (100, 200) and configured to sterilize the suctioned air; a filter assembly disposed in the frame (100, 200) and configured to filter air inside the housing (10, 20); a blower disposed inside the frame (100, 200) and configured to move air inside the housing (10, 20); a flow converter that is disposed on a top surface of the housing (10, 20) and that is configured to guide a flow of air inside the housing (10, 20) and discharge air from inside the housing (10, 20) to an outside of the housing (10, 20); and a guide configured to guide a direction of the flow converter, wherein the sterilizer includes: a sterilizing light source configured to generate sterilizing light, a first sterilizing casing configured to accommodate the sterilizing light source, and a second sterilizing casing that is coupled to a lower portion of the first sterilizing casing and that supports the first sterilizing casing and the sterilizing light source, wherein a portion of the first sterilizing casing is spaced apart from the second sterilizing casing to define a space therebetween that is configured to dissipate heat generated from the sterilizing light source, and characterized in that: a top surface of the first sterilizing casing has a downward slope toward a top surface of the second sterilizing casing from an edge portion to the central portion of the top surface of the first sterilizing casing. a housing (10, 20) including a suction portion configured to suction air from an outside of the housing (10, 20) and a discharge portion configured to discharge air from the housing (10, 20); a frame (100, 200) disposed inside the housing (10, 20); a sterilizer disposed inside the frame (100, 200) and configured to sterilize the suctioned air; a filter assembly disposed in the frame (100, 200) and configured to filter air inside the housing (10, 20); a blower disposed inside the frame (100, 200) and configured to move air inside the housing (10, 20); a flow converter that is disposed on a top surface of the housing (10, 20) and that is configured to guide a flow of air inside the housing (10, 20) and discharge air from inside the housing (10, 20) to an outside of the housing (10, 20); and a guide configured to guide a direction of the flow converter, wherein the sterilizer includes: a sterilizing light source configured to generate sterilizing light, a first sterilizing casing configured to accommodate the sterilizing light source, and a second sterilizing casing that is coupled to a lower portion of the first sterilizing casing and that supports the first sterilizing casing and the sterilizing light source, a sterilizing light source configured to generate sterilizing light, a first sterilizing casing configured to accommodate the sterilizing light source, and a second sterilizing casing that is coupled to a lower portion of the first sterilizing casing and that supports the first sterilizing casing and the sterilizing light source, wherein a portion of the first sterilizing casing is spaced apart from the second sterilizing casing to define a space therebetween that is configured to dissipate heat generated from the sterilizing light source, and characterized in that: a top surface of the first sterilizing casing has a downward slope toward a top surface of the second sterilizing casing from an edge portion to the central portion of the top surface of the first sterilizing casing.