曹源寺, Buddhist temple in Toyoake, Japan.

Sogen-ji is a Soto Zen Buddhist temple in Toyoake, Aichi Prefecture, founded in 1505 by the monk Jitsuda Iun. Its two-storey gate (sanmon), built in 1717 with zelkova and some cypress wood under a hip-and-gable tiled roof, is a Toyoake City designated cultural property. The large kitchen building (daikuri), rebuilt in 1805, retains its Edo-period timber roof framework.

Tradition holds that the site began as a Tendai temple in the Kamakura period. It became a Soto Zen temple in 1505 under the priest Jitsuda Iun. In 1560, during the Battle of Okehazama, the second abbot, Kaio Ryuki, had the roughly 2,500 war dead buried and given funeral rites. A fire on 3 March 1654 destroyed all the halls except two gate doors, and the temple was later rebuilt on its present higher ground.

Sogen-ji is the first stop on the Chita Shikoku pilgrimage, a circuit of 88 temples founded in 1809 by the monk Ryozan of Myoraku-ji after a dream of Kobo Daishi. The temple keeps the statue of Kobo Daishi that the pilgrim Takeda Yasubei brought here, and it holds the Daikon-taki rite every 29 November, when blessed daikon are served with kelp to some 6,500 visitors.

The grounds are easy to navigate on foot, with pathways clearly defined and naturally flowing through the temple property. Comfortable walking shoes are recommended since the site has uneven terrain and visitors will encounter different ground surfaces throughout the garden.

Sogen-ji holds the memorial tablets of Imagawa Yoshimoto, killed at Okehazama in 1560, and of Matsui Munenobu, under the posthumous names Tenzakuin and Jakuo Hakkuan respectively. The temple's second abbot, Kao Ryuki, had the war dead buried and led the rites, and the Senshi-zuka mound is still honoured in a ceremony on the first Saturday of June.