The paper is dealing with the constitutional and historical importance of Act I. of 1946. In 1946 Hungary has changed its form of government. The passage of Act I of 1946 has defined Hungary’s form of government as a republic. In addition to the creation of a republic, the legislation provided powers for the president of the Hungarian Republic. Moreover, the Preamble of Act I. of 1946 was the first document in the Hungarian constitutional history which summarized and declared the most important natural and inalienable rights of the citizens.