Disclosed herein are a washing machine and a method for controlling a washing machine. The washing machine may include: a body; a tub provided inside of the body to store water; a detergent supply unit disposed adjacent to the tub to supply detergent to the tub during an operating mode for washing laundry and to receive water during a cleaning mode; and a controller configured to allow a cleaning of the detergent supply unit to be performed by controlling a flow of water of the detergent supply unit and the tub during the cleaning mode of the detergent supply unit.The present disclosure may be possible to keep the washing machine clean by automatically cleaning a detergent supply unit. In addition, it may be possible to improve the quality and the reliability of the product by automatically cleaning a detergent supply unit by using an input.