To make possible to remove foreign matter falling between a rotary drum and an outer tub easily and to improve watertightness and workability by surrounding the rotary drum having a rotary shaft in a nearly horizontal direction and a roughly depressed heating body storage at the bottom of the outer tub.

Washing water in an outer tub 21 is heated by applying power to a heater 22 while keeping it at a constant temperature. The outer tub 21 has a nearly circular cross section around the rotary shaft 4, and as the rotary drum 1 and the outer tub 21 are structured so as to be concentric in shape perpendicular to the rotary shaft 4, the outer tub 4 can be made small. There is no needless space between the rotary drum 1 and the outer tub 21, the quantity of water supplied to the outer tub 21 can be decreased, it can be heated in a very short time. In case foreign matter falls between the rotary drum 1 and the outer tub 21 by accident, the foreign matter falls to the heating body storage at the bottom of the outer tub 21 and can be removed by loosening a screw from the front and removing the heater 22.