An intrinsic feature of a pre-modern society is its diversity of industries and segregated markets. Segregated markets more likely fail in coordination for development. However, if a concentrated market is exogenously formed and the market could provide the only price to local markets, the market can work as a pivot of coordination for economic growth. Treaty port markets imposed on nineteenth century Japan worked as the pivot and ignited Japan’s industrialization. This work examines the silk-reeling industry, which was the major exporter and led Japanese industrialization, and the role of the treaty port for its development. While there is a consensus about the positive impact on economic growth of free trade forced on East Asia in the nineteenth century, the critical role of the concession market has not gained proper attention. This paper focuses on this market.