A robot cleaner that sweeps dust on the floor toward its center and absorbs the dust through a small-area inlet with a strong suction force, by a cleaning tool that integrates functions of side brushes and a main brush into one. The present disclosure also provides a robot cleaner that enables a large-diameter foreign material to be guided to and effectively absorbed through the inlet without interference by a cleaning tool. The robot cleaner includes a main unit including a fan motor and a dust collector and having an inlet arranged on a base to absorb foreign materials, and a cleaning tool arranged in the bottom of the base, extending to a front side of the base from the inlet and guiding a foreign material on a floor to a side of the inlet, wherein the cleaning tool is arranged to be movable by an external force.