Abstrak The research due to the role of Special Region of Yogyakarta in attempt to defending the independence of Republic of Indonesia in 1945-1949. The author used the historical method to the main issues that will be studied is “how the role of the Special Region of Yogyakarta in attempt to defendIing the independence of Republic of Indonesia in 1945-1949?”. The results showed that Yogyakarta has a major role in the history of the struggle of the Republic of Indonesia at the time of the revolution. Mandate of 5 September 1945 issued by Sri Sultan Hamengku Buwono IX states that the Sultanate of Yogyakarta joined the Republic of Indonesia. The return of Dutch to Indonesia caused Jakarta as the central government the capital of the Republic of Indonesia move to Yogyakarta on January 4, 1946. Since then Yogyakarta become a political game site for the goverment of the Republic of Indonesia. Because of the role then government determine the status of Sultanate of Yogyakarta to Special Region of Yogyakarta.