An air cleaner, comprising: a first air cleaning module having a first fan, a first filter and a first discharge portion; a second air cleaning module having a second fan and a second filter, the second air cleaning module being provided vertically over the first air cleaning module; an air flow controller provided at an upper side of the second air cleaning module and including a circulation fan; a sensor configured to sense a pollution level in a room space; an input configured to receive input of a command for an operation mode of a plurality of operation modes to operate the first and second air cleaning modules (100, 200), and the air flow controller; and a controller configured to drive at least one of the first fan, the second fan, or the circulation fan selectively and configured to determine an amount of discharge air flow, wherein based on at least one of an operation mode input or the pollution level, the controller operates one of the first fan, the first and second fans, the first and second fans and the circulation fan, or the second fan and the circulation fan, characterized in that: the air cleaner further comprises a dividing device provided between the first air cleaning module and the second air cleaning module, the dividing device including a dividing plate arranged to separate air flow generated in the first air cleaning module and air flow generated in the second air cleaning module, the first and second air cleaning modules (100, 200) are spaced apart from each other in the vertical direction by the dividing plate, and air discharged from the first discharge portion is guided by the dividing plate to flow to the outside of the air cleaner. a first air cleaning module having a first fan, a first filter and a first discharge portion; a second air cleaning module having a second fan and a second filter, the second air cleaning module being provided vertically over the first air cleaning module; an air flow controller provided at an upper side of the second air cleaning module and including a circulation fan; a sensor configured to sense a pollution level in a room space; an input configured to receive input of a command for an operation mode of a plurality of operation modes to operate the first and second air cleaning modules (100, 200), and the air flow controller; and a controller configured to drive at least one of the first fan, the second fan, or the circulation fan selectively and configured to determine an amount of discharge air flow, wherein based on at least one of an operation mode input or the pollution level, the controller operates one of the first fan, the first and second fans, the first and second fans and the circulation fan, or the second fan and the circulation fan, characterized in that: the air cleaner further comprises a dividing device provided between the first air cleaning module and the second air cleaning module, the dividing device including a dividing plate arranged to separate air flow generated in the first air cleaning module and air flow generated in the second air cleaning module, the first and second air cleaning modules (100, 200) are spaced apart from each other in the vertical direction by the dividing plate, and air discharged from the first discharge portion is guided by the dividing plate to flow to the outside of the air cleaner. the air cleaner further comprises a dividing device provided between the first air cleaning module and the second air cleaning module, the dividing device including a dividing plate arranged to separate air flow generated in the first air cleaning module and air flow generated in the second air cleaning module, the first and second air cleaning modules (100, 200) are spaced apart from each other in the vertical direction by the dividing plate, and air discharged from the first discharge portion is guided by the dividing plate to flow to the outside of the air cleaner.