Kakugen (1000 - September 20, 1065) was a Japanese Buddhist monk of Shingon Sect in the late Heian period. His father was the Emperor Kazan.
He studied and became a monk under Myokan of Daigo-ji Temple, and thereafter received kanjo (ceremony to be the successor) from Shinkaku and Ningai. In 1030, he was appointed to Denpo Ajari (a master in Esoteric Buddhism) and was inaugurated as the chief priest of Daigo-ji Temple, and subsequently he was conferred the title of Gon Daisozu (a title of high-ranking Buddhist monk). He was appointed to Homu (director of temple affairs) of To-ji Temple in 1048, resided at Todai-ji Temple in 1059 and was conferred the title of Gon no Sojo (a title of high-ranking monk) in 1062.