Daikaku-ji (大覚寺 Daikaku-ji?) is a Shingon Buddhist temple in Ukyō-ku, a western ward in the city of Kyoto, Japan. The site was originally a residence of Emperor Saga (785-842 CE), and later various emperor conducted their cloistered rule from here. The Saga Goryū school of ikebana has its headquarters in the temple. The artificial lake of the temple, Ōsawa Pond, is one of the oldest Japanese garden ponds to survive from the Heian period.
The origins of the temple dates back to the Heian period in the year 814 CE, when Emperor Saga had a palace, known as the Saga-in, constructed on the site. The palace later became his seat of retirement, known as Saga Rikyu imperial villa. According to tradition, when Japan suffered a serious epidemic, the Buddhist monk Kobo Daishi, the founder of Shingon Buddhism, suggested that the Emperor Saga personally copy an important Buddhist religious document called the Heart Sutra (Hannya Shingyō). The emperor made a handwritten copy, and the epidemic is said to have ended. The handwritten sutra is kept at the Shingyōden hall of the temple, and is displayed to the public once every sixty years, the next time being in 2018. Pilgrims still come to the temple to make copies of the sutra, which are kept in the temple with the original.
In 876, thirty-four years after the death of Emperor Saga, his daughter Princess Masako (正子内親王; 810-879), who was consort of Emperor Junna, turned the complex into a temple and gave it the name Daikaku-ji. It was a monzeki temple (門跡), which means by tradition that only imperial princes were appointed abbot of the temple. Over the years, it became the retirement home of several emperors. In the 13th and 14th centuries the temple became the residence of retired emperors such as Emperor Go-Saga, Emperor Kameyama and Emperor Go-Uda, who could be ordained as monks, but continued to wield power in what became known as cloistered rule.