The instructors who use the case method are clearly required to bear a heavier burden of class preparation compared to regular lecture-style classes. Through examining examples of the two representative business schools that have been practicing school-wide case method education in the US and Japan?Harvard Business School (HBS) and Keio Business School (KBS), this study clarifies the institutional support system and mechanism that are functioning in both schools in support of the activities of individual instructors outside class hours for the purpose of improving class quality. Study results confirm that three types of institutional support measures are in place and functioning effectively at both HBS and KBS: 1) acquisition of teaching skills with cases; 2) case writing; and 3)preparation of case analysis and class planning. With the measures, programs using the case method can succeed in producing future managers, which is the school mission of both schools. Institutional support of both schools has been characterized by a shift of focus from informal and irregular support at early stages to formal and regular support as the schools expand and build on their history. In addition, the institutional support is on the basis of culture of teaching, which has been influenced by school founders and key persons as well as in their published works. This study implies that "the quality of education can be improved only when institutional measures and efforts are undertaken to ensure the effectiveness of a teaching method," rather than dependent on simple "selection of an appropriate teaching method". This finding will help deepen discussion on "management for teaching and learning," a topic that has begun to receive more attention among educational researchers in recent years.