Objectives The Committee on Public Health Nursing (2017-2018) of the Japanese Society of Public Health aimed to elucidate the competencies of public health and public health nursing to provide basic materials for public health, public health nursing education, practice, and research.Methods We studied the core competencies of public health professionals and public health nursing in the United States and examined similarities to and differences from those in Japan.Results The United States and Japan shared similar public health and public health nursing competencies in that they targeted populations, identified health problems, and clarified health challenges for effective actions. However, differences were noted in the understanding of target groups, perspectives for identifying health problems and overcoming health challenges, and conceptualization of individuals in populations. In public health, the target population practiced clear boundaries, such as residing in certain geographical areas and ethnic groups, among others. In health challenges, the top-down approach was employed to resolve health problems in certain populations. The individual was recognized as a part of a population composed of a certain group. In public health nursing, target population (e.g., from individuals/families to groups/communities/social groups) were understood in a continuous and multilayered manner. Individual/family health problems were associated with the characteristics of groups, communities, and social groups that encompass the continuum. Moreover, health challenges were addressed in a manner oriented toward the transformation of social groups as a whole. Public health nursing competencies in both countries, which share many similarities, were developed to achieve the objectives of public health. In the United States, the competencies and skills considered necessary, such as analytical/assessment and cultural competency skills, were clearly expressed and constructed in line with the core competencies of public health professionals. However, in Japan, skills and abilities necessary as competencies in public health nursing mentioned above were not specified.Conclusion Elucidating the core competencies of public health professionals in Japan is essential to develop human resources that can contribute to effective practices in public health and public health nursing. Toward this end, skills and abilities necessary as competencies in public health nursing in Japan, which were not previously verbalized, should be described in detail.