Abstract: An ice making machine has an ice making unit including an evaporator, a water tank for containing raw water to be iced, a water distributor for supplying the water to the ice making unit, a circulation pump in fluid communication with the water tank and the water distributor for supplying water from the water tank to the water distributor during an icing operation, a water supply system for supplying water to the water tank, a sub-tank fluidly communicated with the water tank, and a water level control device disposed within the sub-tank for monitoring the water level therein to detect a predetermined water level. A flushing pipe for supplying a washing water to the sub-tank is connected thereto through an air supply device.