Disclosed is a robot cleaner capable of reducing the material cost thereof by use of fewer motors, and performing wet cleaning while travelling in all directions and rubbing the floor surface, the robot cleaner includes a plurality of motors generating driving forces, a plurality of pad assemblies configured to rotate by receiving a driving force from one of the plurality of motors, and provided in a tilted manner so that a bottom surface of each of the plurality of pad assemblies has an uneven frictional force with respect to a floor surface, and a tilt gear unit configured to simultaneously vary tilting directions of the plurality of pad assemblies by receiving a driving force from another one of the plurality of motors, wherein the robot clean can travel in all directions depending on a tilting direction and a rotational direction of each of the plurality of pad assemblies.