Trade Specialization Index (TSI) is employed to analyze the position or stage of product development. TSI index can describe certain types of products, whether Indonesia has a tendency to be the exporting or importing country. The purpose of this study was to analyze the Indonesian Seaweed Trade Specialization Index. The data were obtained from the secondary data, namely the UN Comtrade in 2017 and 2018. The data presented the value of seaweed commodity exports to all countries in the world and the value of seaweed imports during 2017 and 2018. The formula used in analyzing this Trade Specialization Index was the Indonesian export value minus the import of seaweed then the result was compared to the total value of exports and imports of Indonesian seaweed. The calculation results indicated that the Indonesian Seaweed Trade Specialization Index was 0.93. This suggests that Indonesia has strong competitiveness or Indonesia has a tendency to be an exporter of seaweed commodities. Therefore, it can be concluded that Indonesian seaweed supply is greater than domestic demand.