Disclosed herein is an air cleaner capable of being coupled or separated in a vertical direction to improve space utilization. An air cleaner may include a first air cleaning module provided with a first connection unit, and a second air cleaning module detachably coupled to the first air cleaning module and provided with a second connection unit, wherein the second connection unit is configured to be detachably coupled to the first connection unit, and configured to be rotatable with respect to the first connection unit when the second connection unit is coupled to the first connection unit.