A control method for a robot cleaner that includes: driving a driving part to move the robot cleaner by a predetermined distance in an opposite direction to a proceeding direction thereof when a bumper sensor detects a collision with an obstacle, measuring the number of times in which the robot cleaner repeats moving in real-time, comparing the measured number with a predetermined reference number, and stopping the robot cleaner when the measured number is more than the reference number. With this method, the robot cleaner can diagnose a breakdown of the bumper sensor to stop the cleaner, and inform a user of the breakdown.