 Born in Machecoul, Landreau graduated from the Nantes Atlantique "Centre of Excellence" in La Jonelière.His first professional match for Nantes was a 0–0 draw against Bastia on 2 October 1996 and saved the penalty from Ľubomír Moravčík.Since 1996, he remained a mainstay in the Nantes starting line-up, and consistently produced excellent performances.