"We should support him," Putin told a gathering of more than 2,000 lawmakers, government officials and foreign diplomats.
"Now, it is very important to altogether continue the already chosen course of the country's development, guided by the citizens' interests, which has already justified itself," he said.
Taking the oath of office, Medvedev pledged to "respect and protect the rights and liberties of every citizen," observe the Russian constitution and serve the people "faithfully."
In his speech after taking the oath, he promised to promote civil and economic freedom and bring the country to the best countries' club.
"I consider it my primary task the protection and further development of civil and economic freedoms and the creation of new great opportunities for people's self-fulfillment," he said.
"During the past eight years, we have set up strong foundations for long-term development, for decades of free and stable development," he said.
"The unique chance is something we must use to maximum, so that Russia would become one of the best countries in the world... This is our strategy and guidelines for years to come," he said.
Medvedev also pledged to promote the rule of law, eliminate corruption, improve people's living standards and stimulate private investment, as well as industrial and agricultural growth.
In honor of the inauguration, a 30-gun salute was fired. The presidential regiment was presented to Medvedev and Putin on the Cathedral Square in front of the Great Kremlin Palace. The inauguration ceremony lasted less than half an hour.
Medvedev, a former law professor and first deputy prime minister, swept the March 2 elections thanks to Putin's endorsement. He has pledged to continue the policies set by his predecessor Putin.
Russia's Viktor Zubkov-led cabinet rendered its resignation soon after Medvedev took office. Zubkov signed the order in compliance with the Russian Constitution and relevant laws, said the Cabinet's press-service.
About two hours after becoming president, Medvedev nominated Putin to be prime minister. The State Duma Speaker Boris Gryzlov said that the lower house of the parliament would hold an irregular meeting on Thursday to approve Putin's nomination.
In accordance with the Constitution of the Russian Federation, Medvedev has instructed the Russian government to continue to act until the formation of a new cabinet.
(Xinhua News Agency May 8, 2008)