Juntoku Tennō (順徳天皇) (October 22, 1197 - October 7, 1242) was the 84th emperor of Japan, according to the traditional order of succession.
He reigned between the years 1210 and 1221. Prior to his ascension to the Chrysanthemum Throne, his personal name (imina) was Imperial Prince Morinari (守成親王 Morinari-shinnō).
He was the third son of Go-Toba Tennō. His mother was Shigeko (重子), daughter of Fujiawara Hanki.
Imperial Prince Morinari became crown prince in 1200. In 1210 he assumed the throne as the Juntoku Emperor, after constant pressure from his father, Emperor Go-Toba to abdicate his older brother, Emperor Tsuchimikado.
During Emperor Juntoku's reign, his father assumed effective power as a cloistered emperor.
In 1221, he was forced to abdicate due to his involvement in the Jōkyū War; a failed incident in which Emperor Go-Toba sought to overthrow the Kamakura shogunate and proclaim imperial restoration.
Emperor Juntoku was sent into exile on the island of Sado, where he remained until his death in 1242.
The emperor was posthumously known as Sado-no In (佐渡院), due to his last years in exile on Sado. He was buried in the Mano Goryo mausoleum in the west of the island. The official Imperial Tomb of Emperor Juntoku is in Kyoto.
He was a disciple of Fujiwara no Sadaie, who taught him poetry. One of the emperor's poems was included in the poetry anthology, Ogura Hyakunin Isshu.