Nitish Kumar was sworn in as Bihar chief minister for a fourth straight term on Monday at Raj Bhawan in Patna.
Union Home minister Amit Shah and BJP chief Jagat Prakash Nadda were among others present at the oath-taking ceremony.
The RJD and Congress decided to boycott the event.
BJP leaders Tarkishore Prasad and Renu Devi took oath as the deputy chief ministers of Bihar.
Kumar and other ministers were administered the oath of office by governor Phagu Chauhan, a day after he staked claim for the formation of a new government in the state.
The 69-year-old has had a continuous run since November, 2005. There was a short break in 2014-15, when the post was occupied by Jitan Ram Manjhi.
JDU leaders Vijay Kumar Choudhary, Vijendra Prasad Yadav, Ashok Choudhary, and Mewa Lal Choudhary took oath as Cabinet Ministers.
Santosh Kumar Suman, son of Hindustani Awam Morcha (HAM) chief Jitan Ram Manjhi and Mukesh Sahni of Vikassheel Insaan Party (VIP) were also among those who took the oath. From the BJP, Mangal Pandey and Amarendra Pratap Singh took oath as Bihar Cabinet Ministers.