PURPOSE: To enhance the washing ability by compensating a washing time or a soaking time so as to obtain an optimum washing time or soaking time in accordance with a water temperature when a previously set washing time is selected in accordance with degrees of output signals indicating a degree of wash-off of dirt, and a transmittance of water after the variation rate of degree of dissolution of detergent is saturated, and a saturation time.

CONSTITUTION: A control device comprises a transmittance detecting means 10 composed of a light emitting element and a light receiving element, for detecting a contamination of washing water or the like, a washing volume detecting means for determining a volume of washing in a washing tub spin basket, a temperature sensor 15 for detecting a temperature of water in a washing tub/spin basket, and a process control means 11 adapted to receive outputs from the transmittance detecting means 10, the washing volume detecting means 13 and the temperature sensor 15, for changing the washing process and the time of reversing of agitating blades 3. Further, the process control means 11 controls the washing time, the soaking time and the like in accordance with a degree of washing of dirt and a degree of dissolution of detergent which are detected in accordance with variations in transmittance, a water temperature and a volume of washing detected by the temperature sensor 15 and the like.