Disclosed are a robot cleaner. The robot cleaner includes: a cleaner body configured to move in an area and clean the area; and a sensor assembly provided in the cleaner body. The sensor assembly includes: a main sensor configured to be moveable between a sensing position where the main sensor protrudes out of the cleaner body and a settled position where the main sensor is inside the cleaner body; a sensor position changer configured to allow the main sensor to move between the sensing position and the settled position; and a stopper configured to restrict the sensor position changer from allowing the main sensor at the sensing position to move towards the settled position.