After the independence of Indonesia, Setiadi Reksoprodjo still maintained his job at the West Java Transportation and Irrigation Bureau. He was also involved in politics, and joined the Indonesian Socialist Party. In 1945, he became the chairman of the Socialist Youth of Indonesia — the party's youth wing — in Cirebon. He was also appointed as the Chairman of the Indonesian National Committee of Cirebon and as the Chairman of the Cirebon Defence Council.