Socialist Francois Hollande has been elected as France's new president.
He got about 52% of votes in Sunday's run-off, according to early projections, against 48% for centre-right incumbent Nicolas Sarkozy.
Mr Sarkozy has admitted defeat, saying: "Francois Hollande is the president of France and he must be respected."
Analysts say the vote has wide implications for the whole eurozone. Mr Hollande has vowed to rework a deal on government debt in member countries.
Exuberant Hollande supporters have already converged on Place de la Bastille in Paris - a traditional rallying point of the Left - to celebrate.
Mr Hollande capitalised on France's economic woes and President Sarkozy's unpopularity.
The socialist candidate has promised to raise taxes on big corporations and people earning more than 1m euros a year.
He also wants to raise the minimum wage, hire 60,000 more teachers and lower the retirement age from 62 to 60 for some workers.
In his concession speech, Mr Sarkozy told stunned supporters that he was "taking responsibility for defeat.
Hinting about his possible political future, he said: "My place will no longer be the same. My involvement in the life of my country will now be different."
During the campaign, he said he would leave politics if he lost the election.
It is only the second time an incumbent president has failed to win re-election since the start of France's Fifth Republic in 1958.
The last was Valery Giscard d'Estaing, who lost to socialist Francois Mitterrand in 1981. Mr Mitterrand had two terms in office until 1995.
The new president is expected to be inaugurated later this month.
A parliamentary election is due in June.----
Live coverage: http://www.bbc.co.uk/news/world-europe-17958367
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