This research focuses on the rivalry between Japan and China in the Jakarta-Bandung high-speed railway infrastructure project. Although the project was initially offered by the Indonesian government to Japan, this project eventually was won by China. The purpose of this study is to find out what factors encourage the decision of the Indonesian government to choose China over Japan as the strategic partner in this mega infrastructure project. This research uses the process-tracing method in analyzing decisions taken by the Indonesian government. This article finds that domestic politics such as perceptions of power, state’s domestic characteristics, and quality of political leadership as well as external factors such as the influence of China in Asia and the limitations of Japan in fulfilling the requirements given by the Indonesian government drive Indonesia’s decision to choose China over Japan despite Japan’s technological superiority in infrastructure project implementation.