The September 2006 Democratic Party of Japan presidential election was held on 25 September 2006 in accordance with the end of the presidential term which had commenced in 2004. Incumbent president Ichirà  Ozawa, who took office in April, was re-elected unopposed.
Ozawa was elected president in April, defeating Naoto Kan by a large margin. He sought to unify the party by dividing responsibility, appointing Kan and Yukio Hatoyama to key roles. On 23 April, shortly after taking his post, Ozawa oversaw victory for DPJ candidate Kazumi Ota in the highly anticipated Chiba 7th by-election, a major turnaround in the party's fortunes. The three leaders made public appearances together throughout the year, including a meeting with Chinese premier Hu Jintao in July, promoting a harmonious image.
Ozawa was expected to be re-elected unopposed. He was endorsed by Kan and Hatoyama, as well as Yoshihiko Noda and former president Seiji Maehara, who represented junior and mid-ranking legislators who often rebelled against senior leadership. Popular former president Katsuya Okada also declined to stand. Some members advocated for at least a token contest in order to compete with headlines from the Liberal Democratic Party's leadership contest, which was taking place at the same time. Names such as Akira Nagatsuma and Keiichiro Asao were floated, but all chose not to run. Ozawa officially announced his re-election bid on 28 August.
Ozawa was the only candidate to stand when nominations were taken on 12 September. He was confirmed without a vote at the party convention on 25 September. He declared his biggest goal was to win the 2007 upper house elections the following summer.
Social Democratic Party leader Mizuho Fukushima, People's New Party leader Tamisuke Watanuki, and New Party Nippon leader Yasuo Tanaka attended the convention as guests, indicating Ozawa's intention to coordinate with other opposition parties for upcoming elections.