The ceremony at the presidential palace in New Delhi was notable for the presence of Pakistani Prime Minister Nawaz Sharif, who reportedly ignored warnings from his own intelligence agency to attend. Relations have been tense between the two nuclear-armed rivals.
President Pranab Mukherjee administered the oath to Modi and his cabinet ministers. "I, Narendra Damodardas Modi, swear in the name of God that I will maintain the integrity of India," Modi said in Hindi. "I will work without fear, anger or hatred and will do justice to all as per the constitution."
Modi, 63, who had been chief executive of the western state of Gujarat, led the Bharatiya Janata Party to victory in India's parliamentary elections earlier this month, ousting the long-ruling Congress Party led by Rahul Gandhi, former Prime Minister Indira Gandhi's grandson.
The Congress Party was blamed for a weak economy and persistent corruption. The BJP was elected on a promise of running a cleaner, more business-friendly government.
For the first time, India invited the heads of state of the entire, eight-nation South Asian Assn. for Regional Cooperation to the ceremony, and all sent representatives.
However, it was the presence of
"It is a great moment and a great opportunity," Sharif told the NDTV network on his arrival in Delhi. "This is a chance to reach out to each other. Both governments have a strong mandate. This could help in turning a new page in our relations."
Modi and Sharif were expected to have bilateral talks Tuesday.
Other dignitaries included Sri Lankan President Mahinda Rajapaksa, Afghan President
Security for the ceremony was tight, and included a special team of commandos and paramilitary forces among more than 7,000 members of security forces on duty.
With Modi riding a surge of popularity, especially among young voters, the BJP won 282 seats in the 543-seat parliament, the biggest mandate ever for a non-Congress Party government. With more than a majority, the BJP will be able to govern without allies.
Earlier in the day, Modi paid a visit to Rajghat, Mahatma Gandhi's memorial, to pay his respects. Born in 1950, Modi is the first prime minister to be born in an independent India.