The purpose of this study is to examine the factors that could best explain the initial superiority the Imperial Japanese Navy (IJN) achieved during World War II through military innovation. For this purpose, the thesis analyzes the factors that most significantly impacted the Japanese aircraft carrier and aircraft innovation during the interwar period. The study found that technology, international relations, and adaptation positively influenced military innovation in the IJN in various ways. With the newly developed aviation technology, the IJN laid the groundwork for military innovation, which aided response to the two naval disarmament treaties; through the Second Sino-Japanese War, the IJN elaborated its aircraft and aircraft carrier doctrine. In other words, the IJN's military innovation in the interwar period was enabled by technology, driven by the realist/international relations theory, and enhanced by adaptation. This study strengthens existing research on military innovation by examining positive factors and suggesting considerations for establishing defense policy.