The concept of trust underlies an important part of various theories in International Relations, but is yet to take roots in the mainstream research. To fill this gap in the literature, this study first reviews the dominant theories on trust in sociology and psychology, and then identifies the three main approaches to trust in world politics. In order to find the factors affecting state-to-state trust, the study tests the effects of leadership turnovers on the formation of trust or mistrust between two states. In particular, the empirical research focuses on the relations between China and Japan under different leaderships from 2009 and 2019. It uses an original dataset of high-level Sino-Japanese diplomatic activities and talk content from 2009 to 2019, as extracted from the Chinese newspaper People’s Daily as well as the websites of the ministries of foreign affairs of both China and Japan. The findings highlight how interstate mistrust is likely to endure different leadership changes whereas interstate trust is unlikely to be inherited so easily between leaderships. Trust between China and Japan is found to be highly contextual and dependent on the core state interests and the political actors involved. Mutual trust, if established, can move the relationship beyond the commercial realm and into more strategic area. The study contributes not just empirical evidences on the role of trust in interstate interactions but also a systematic method to assessing such interactions.