A vacuum cleaner includes: a body case having an outer circumferential surface formed along either a circular arc or a polygon; a drive wheel allowing travel of the body case on a cleaning target surface; a side brush provided to the body case to be movable in a certain direction. The side brush: projects from the outer circumferential surface of the body case by an amount that changes in response to movement; includes a brush body movable to retreat toward the outer circumferential surface of the body case in response to external force acting in a direction crossing the certain direction; and includes a cleaning unit rotatably provided to the brush body. The cleaning unit rotates to clean the cleaning target surface. The side brush projecting from an outer circumferential surface of a body case can retreat readily and reliably when the side brush contacts an obstacle.