Abstract: The dishwasher according to the present invention has two operation courses: one course adapted for using a low-foaming dedicated detergent; and the other course adapted for using a high-foaming kitchen detergent. In the kitchen detergent course, the dishwashing operation includes a first mode of the “spray and wait” process carried out as a preliminary washing operation, including the steps of spraying the water containing a detergent onto the dishes for a short period of time and subsequently halting the spray for a certain period of time. During this process, the amount of the foam present within the wash chamber is determined by means of a photosensor located within the drying duct. If there is a large amount of foam, a longer period of time is set for draining the detergent water. After the water is drained for the aforementioned period of time, fresh water is supplied to a predetermined level.