PURPOSE: To improve washing performance and to cause cleanser to surely flow into a washing tank by allowing drained water from a draining pump to be a driving source in a draining process after a pre-washing process is finished.

CONSTITUTION: After the prescribed quantity of the cleanser is put into a cleanser housing part 8 and the housing part is hermetically sealed by a cover 9, objects to be washed such as dishes are housed to a dish basket and operation is started. At first, washing water is supplied and the pre-washing process is executed to press the washing water by a washing pump 3 and to eject the washing water from a washing nozzle 2. Then, dirt stuck to the objects is partially washed off. Next, the draining process is executed to drain the dirty washing water and the washing water in a washing tank 1 is drained from a draining hose 6 to the outside of a washer by a draining pump 5 while being filtered by a filter 4. At such a time, a part of the drained water becomes a branched water flow and flows from a branching route 7 to the cleanser housing part 8 and the cleanser of the cleanser housing part 8 directly receives this branched water flow and flows down to the washing tank 1 without fail. Consequently, the fresh washing water is supplied and a main washing process is executed by the ejection of the washing water including the cleanser which flows into the washing tank 1.