Abstarct: The history of world's fairs has witnessed changes and developments in the world in various fields, including architecture. In this historical course, architectural design approaches have undergone fundamental changes and countries have experienced various goals and strategies. The international arena of world's fair at different times provides countries with opportunities to choose what image they want to present. In this regard, the present dissertation in the form of qualitative research, analytical-explanatory method and with library studies, examining the developments of world's fairs, explains the architectural design approaches in the Japan pavilions throughout the history of this event. Accordingly, the approaches used in the architecture of Japan pavilions, in relation to the architecture of pavilions other countries and the approaches to the world's fairs are examined and the architectural position of this country in this field is assessed. Research in the field of architectural design of Japan pavilions is important because in addition to studying the participation of a prominent and influential country in the developments of the world's fair and creating a research field to strengthen, nurture and expand the knowledge of architectural design in the field of this event, analyzes and explains this particular type of oriental architecture in the international arena. The results show that the architecture of the pavilions in general in the field of world's fairs, depends on the conditions and situation prevailing in the world community as well as the general programs and strategies of the fairs; And in a special way in the field of Japan, depending on the state of the country's architecture at that time as well as the country's developments in various fields; According to the resultant of their characteristics, they have clarified special approaches and historical periods that, in accordance with their content in world's fairs, include the following: 1. Scientific and technical innovations of construction in the pavilion (1889-1851), 2. The combination of industry and art and the use of emerging styles and various historical references in the design of pavilions (1839-1939), 3. The use of the latest achievements of structures, materials and New building structures for solving global problems (1958-1970) and 4. Pursuing sustainable architectural approaches (1992-1995) and in the field of Japan, include the following: 1. Using traditional patterns and styles (1933-1873), 2. Integrating modern style with Japanese patterns (1939-1939), 3. Applying new technologies in combination with new Japanese patterns and approaches (1958-1992) and 4. Paying attention to environmental crises and the development of sustainable architecture (2015-2000). However, the approaches used in the design of Japan pavilions are not structurally and temporally consistent with the various developments and periods of world's fairs; But in recent years (especially in the last period of fairs), this country, with a correct understanding of the programs of the World's Fair, through the architecture of its pavilions has been able to have a strong connection and interaction with the pavilions of other nations of the world. Japan in interaction with other countries and in response to the world's fair approach; In presenting its pavilions, are planned programs such as services and pursuing new issues of sustainable development, the use of new technologies with Japanese models in order to solve global problems and presenting a modern national identity as approaches and strategies of participation in the architectural scene of this field.