In this study, a comparative analysis of national brand image of three different countries is conducted to develop differentiation strategies for Korean national brand. Specifically, the influence of variables such as the extent of economic development of respondents' nations(advanced countries, newly industrial countries and developing countries) and respondents' self-categorization(internal group, external group) with the country being evaluated on national brand images is examined. Results of the study indicated that respondents from newly industrial and developing countries tended to evaluate more highly the overall national brand image constructs(national heritage, global leadership, people, social system) than the respondents from advanced countries. Also, Koreans(internal group) showed more positive evaluation of most of the national brand image constructs on Korea than those on Japan or China (external groups). In order to examine whether the survey findings on the different recognition levels on national brands were actually reflected in establishment of national brand strategies, a preliminary evaluation was performed by conducting in-depth interviews with national brand practitioners. Theoretical and practical implications are also discussed based on the results of the quantitative and qualitative analyses.