PURPOSE: To detect the quantity of a material to be detected, by supplying a certain quantity of another liquid to the material to be detected and agitating them to measure the combined agitation resistance of the material to be detected and the supplied liquid.

CONSTITUTION: The reflected wave of the ultrasonic wave radiated from a transmitter 19 which is attached above a basket 7 of a washing tank is received by a receiver 20 and is processed by amplifying and detecting circuits and is compared with a signal, which is processed in a rounding circuit R.C after the adjustment of the timing in a multivibrator circuit, in a comparator. When the level of the received signal exceeds the level of the rounding circuit, a signal is outputted to a flip flop circuit, and AND between this signal and a clock pulse is sent to a gate circuit to count clock pulses. Thus, when a material to be washed is supplied to a certain quantity of water and is agitated, a length L up to the water surface fluctuated by the vortex due to a pulsator 12 is inputted to an indication controlling part 21, thus using this method for processings such as water level determination.