Protectionist trade policies are increasingly observed in many countries. We need to explore which characteristics of individuals influence support for protectionist policies. For this purpose, we conduct a survey of 10,000 individuals in Japan. This review article summarizes the main findings from our project on trade policy preferences and discusses their policy implications. We confirm the impacts of previously well-established factors, such as occupation, industry, and education, but discover significant effects of behavioral biases. We also detect relationships with regional characteristics. Our research results suggest that various policy measures, not limited to traditional income compensation or insurance schemes, are required to widen support for trade liberalization.