At the end of the 2005–06 Ligue 1 season, Landreau's contract with Nantes was set to expire but Nantes was set to offer Landreau a new contract along with Mauro Cetto and Jérémy Toulalan. He gave a press conference and announced that after thirteen years, he would leave FC Nantes to meet new challenges in a more important team. He announced his intention to leave his first club just before the end of the 2005–2006 season. As his contract expired, Arsenal and A.C. Milan were among interested signing him. During his last match at Stade de la Beaujoire on 6 May 2006, he received a tribute from the fans who saluted his dedication and loyalty to the club for thirteen years. The season following his departure, Nantes was relegated to Ligue 2 for the first time since 1963.