PURPOSE: A robot cleaner is provided to easily eliminate foreign materials stuck for a long time and stains by strongly rubbing a mop on a floor. CONSTITUTION: A robot cleaner(1) comprises a wet cloth cleaner(20), a pushing device(30), and a steam sprayer(40). The wet cloth cleaner is attached or detached to a underside of the main body(10) in the rear part of the main body. The mop is attached to the external side of the wet cloth cleaner. The pushing device pushes the wet cloth cleaner in the inner lower part of the main body to downwards so the mop attached to the external side of the wet cloth cleaner pushes a floor. The steam sprayer is installed inside the main body.
