Recently, various electronic printed circuit boards on which IC and LSI are mounted are required in personal computers (PCs), because of the widening applications of PCs, for example, in the area of education, business, art, and multimedia. To meet this ever-increasing demand, an efficient and convenient method of thermal stress analysis for the printed circuit boards with electronic devices is necessary. Almost all of the thermal stress analysis methods in conventional use employ computational techniques such as the finite-element method or boundary-element method. These methods are not adequate for the design of the electronic printed circuit boards because of their complexity. In this paper, we proposed an effective and convenient method for thermal stress analysis of the printed circuit board by formulating theoretical equations using the beam theory. The method is adopted to analyze thermal stress in a wire lead frame of an electronic device mounted on a printed circuit board, and the efficiency is discussed comparing results obtained by the method and finite-element analysis.