Judan (十段 Jūdan), which literally means "ten dan", is the fourth oldest of the seven big titles in Japanese professional Go. The winner's prize is ¥7,000,000 currently, smallest among the big seven. It is sponsored by the Sankei Shinbun newspaper. All professional players of the Nihon Ki-in and Kansai Ki-in can participate.
Due to the importance of the Judan as one of the "big seven" titles in Japan, there are several paths of automatic rank advancement through it in the Nihon Ki-in new promotion system. Challenging for the title warrants a promotion to 7-dan, actually winning the title promotes to 8-dan, and finally winning the title twice gives an immediate 9-dan promotion.