Even for electrical appliances, testing for illegal behaviors becomes difficult since the software system in an electrical appliance has already, become large in size. Actually the conventional method cannot generate sufficient test items for illegal behaviors. But testing illegal behaviors becomes more and more important, since the failure of electrical appliances would cause fatal effects on our daily life. We therefore propose a new method for generating appropriate test items to check illegal behaviors, which consists of the following steps: (1) describe software behavior using use case notation; (2) analyze illegal behavior by the deviation analysis technique; (3) construct a software fault tree using the above information; and (4) generate test items from the software fault tree. This paper also reports the experimental applications to actual development of an electrical appliance. The evaluation results identified that all necessary, test items for illegal behaviors are included in the resultant test items.