<p>The control device (13) for a washing machine is provided to have a function of testing the working characteristic of the transmission sensing device (16) for sensing light transmission of water filled while the water supplied in a washing bath (1) is fresh before putting detergent therein or stirring the cloth for rinsing. The control device (13) makes it possible to automatically test the working characteristic of the transmission sensing device (19) and judge if abnormality takes place when the washing or rinsing operation is executed while the washing machine is in operation. <IMAGE></p>
