An air cleaner comprising: a housing including a suction portion configured to suction air from an outside of the housing and a discharge portion configured to discharge air from the housing ; a frame disposed inside the housing ; a sterilizer disposed inside the frame and configured to sterilize the suctioned air; a filter assembly disposed in the frame and configured to filter air inside the housing ; a blower disposed inside the frame and configured to move air inside the housing ; a flow converter that is disposed on a top surface of the housing and that is configured to guide a flow of air inside the housing and discharge air from inside the housing to an outside of the housing ; 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 including a suction portion configured to suction air from an outside of the housing and a discharge portion configured to discharge air from the housing ; a frame disposed inside the housing ; a sterilizer disposed inside the frame and configured to sterilize the suctioned air; a filter assembly disposed in the frame and configured to filter air inside the housing ; a blower disposed inside the frame and configured to move air inside the housing ; a flow converter that is disposed on a top surface of the housing and that is configured to guide a flow of air inside the housing and discharge air from inside the housing to an outside of the housing ; 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 . <EOS>