Ms Royal is seen by many as a breath of fresh air in French politics (BBC, 30/09/06)
France's Royal seeks presidency
Declaring her candidacy for the nomination of the opposition Socialist Party, she vowed to bring real change.
Ms Royal has a strong lead in opinion polls over her more established male rivals - among them critics who say she lacks political experience.
In November, Socialist party members will select a candidate to run for president next April.
Ms Royal is seen by many as a
breath of fresh air in French politics
The latest opinion poll suggests that Ms Royal is ahead of any of her potential rivals by at least 30 percentage points.
The BBC's Valerie Jones in Paris says she has risen on a wave of grassroots support, and appears to represent a desire amongst voters for a change in French politics.
 I accept taking on this mission for the benefit of France and the trials that go with it  Segolene Royal  |
Announcing her bid at a rally in southern France, Ms Royal pledged to "revive the country" and "give it every opportunity" against the governing conservatives.
"I accept taking on this mission for the benefit of France and the trials that go with it," she said.
Our correspondent says Ms Royal's position seems to have been strengthened by the decision of the failed candidate during the 2002 poll, Lionel Jospin, not to stand again.
Other Socialist candidates have four days to announce they will seek the nomination.
The eventual candidate is likely to face the current conservative Interior Minister, Nicolas Sarkozy, in the presidential poll.
Last Updated: Saturday, 30 September 2006, 14:25 GMT 15:25 UK