The purpose of this study was to measure the dimensions of critical thinking (CT) of nursing students at baccalaureate nursing program and registered nurses at general hospital in Japan. Relevant literature on the current environment of Japanese nursing practice and education is reviewed as it provides the background to the key aspects of dimensions of Japanese nurses' and students' CT. The California Critical Thinking Disposition Inventory (CCTDI) was used to measure the dimensions of CT skills. The convenience sample consisted of three small groups: generic students (n=82) including freshmen and juniors; transfer students (n=16) at selected baccalaureate nursing program; and registered nurses (n=67) at selected general hospital were administered CCTDI. Descriptive statistic indicated that all groups had an ambivalent disposition towards CT in majority of sub-scale while they scored a positive disposition towards CT on several sub-scales. A one-way ANOVA indicated that registered nurses scored lower than other two groups of baccalaureate students on the total score and several sub-scale score. The outcomes of this study propose recommendations regarding curriculum review for Japanese nursing education and reflection on professional boundaries for Japanese nursing practice.