The Flags of the United States of Indonesia refers to the state flags that were used as the official state symbols of the United States of Indonesia (Abbreviation: USI), the predecessor state of the Republic of Indonesia. The flag that were hoisted during the proclamation of independence on 17 August 1945 remained as the official flag of the United States of Indonesia after its on December 27, 1949 and it was written on the Federal Constitution of 1949.