A robot cleaner capable of vacuuming foreign materials on a floor includes a main body to which a dust collector is mounted and a vacuuming unit provided at a front portion of the main body to clean a floor. The vacuuming unit is configured to move relative to the main body. If it is determined that the robot cleaner is located near a wall or an obstacle, the vacuuming unit moves to the wall or the obstacle. Since the vacuuming unit contacts the wall or the obstacle, a region of a floor near the wall or the obstacle may be cleaned. Further, a manual cleaner may be selectively connected to a channel connector of the robot cleaner so that a user may choose automatic or manual cleaning of a floor at the user's convenience.