This paper presents some results gained from our investigation of reliability analysis for automotive electronic systems with the aim of establishing a method for application to reliability engineering.As the functions of automotive electronic systems expand to various areas, the number of components increases. Therefore, the total failure rate necessarily increases, so that it is important to reduce the effects of a failure as well as to prevent failure occurrence. In consequence, the component duplication concept has been implemented as a countermeasure. Through this investigation, a reliability analysis method for automotive electronic systems with certain duplicated components and the applicability of this method have been established. Moreover, in applying reliability technology, various points to be taken into consideration have been defined.