The core issue of ethical problem solving in engineering is to understand what exactly happened and to define its nature. Problems often arise mostly in morally complex situations. Traditional philosophical theories usually focus on extreme conflicts of interest and suggest moral theory-centered problem solving methods. However, these methods are not only difficult to specifically apply to real situations, but also are likely to fail to deal with actual moral issues in engineering fields. This study aims to develop more desirable ethical problem solving methods, based on STS (Science and Technology Studies) and engineering ethics combined. First, we have examined the engineering ethics with implications of an STS perspective, then have analyzed traditional ethical problem solving methods in a critical point of view. This study will suggest a new ethical problem solving method named Matrix Guide, based upon those analyses. Specifically, this study classifies four stages of problem definition, analysis, solving, and feedback. Here, we focus on how to combine technological and non-technological factors in each stage, when we are facing morally complex situations in engineering sectors.