"I decided to stop because it's time for change," he told a news conference. "Something inside me says it's the moment to take a different path because I think I have fallen out of love with this girlfriend who has been with me all these years."
Alguersuari made his F1 debut with Toro Rosso in 2009 at the age of 19 years and 125 days. The record stood until this season when Dutch 17-year-old Max Verstappen made his first appearance for the same team.
The Spaniard left Formula One at the end of the 2011 season and most recently competed in the Formula E electric series.
After fainting following a race in Moscow in June, he withdrew from the final races in London on health grounds.
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"I could continue competing but I'm stopping," said Alguersuari who has long spent his spare time working as a DJ and composing music, adding that he had no concerns about his health.
"I could stay just for the money but I need a change. What makes me happy is music, I am going to make music."
(Reporting by Alan Baldwin in London, editing by Tony Jimenez)
