A robot cleaner capable of improving the external esthetic quality thereof while enhancing the cleaning performance, the robot cleaner including a body configured to remove dust while navigating on a floor and to form an external appearance of the robot cleaner, and a side brush assembly installed at the body to clean corners of the floor, wherein the side brush assembly includes a motor configured to supply a power while being installed at the body, a rotation shaft coupled to the motor, and a plurality of side brushes rotatably coupled to the rotation shaft, and wherein the plurality of side brushes have respective intervals changed with respect to one another such that the plurality of side brushes are prevented from being exposed to outside the body.