Abstract: The purpose of this study is to determine whether different levels of product diversification have an impact on internationalization strategies. We conducted a case study that included three food companies that have different positions regarding the features of internationalization and product diversification. We found three obstacles to the progress of overseas expansion in the food manufacturing industry in Japan. Based on the literature review, it seems that performance becomes high as product and market diversification is increased. However, under certain circumstances, these merits can also have limits.