A robot cleaner includes a rolling cleaning module including a rolling member configured to rotate clockwise or counterclockwise when viewed from a left side while in contact with a floor, a sensor unit, and a controller configured to detect a change in position of the robot cleaner and a change in load current of a motor connected to the rolling member based on data detected by the sensor unit. When there is a change in position and a change in load current, a specific area of a floor is determined to be a contaminated area.