
The 68-year-old cleric kissed the Qur'an and took the oath of office before Majlis (parliament) lawmakers, foreign dignitaries and senior Iranian politicians.
The inauguration ceremony was aired live from Iranian state TV.
Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei on Thursday gave official seal of approval to President Rouhani who won a landslide victory and was re-elected as next president on May 19 presidential election.
Iranian government declared one day holiday in the capital, Tehran to prepare the grounds for presidential inauguration ceremony.
Several foreign guests, heads of states and high ranking officials including the High Representative of the European Union for Foreign Affairs and Security Policy Federica Mogherini are taking part in President oath-taking ceremony.
Rouhani was re-elected for a second term in office on May 19, for another four years, sweeping over 23 million or 57 percent of the votes.
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