Kanjizaiō-in (観自在王院) was a Buddhist temple located in Hiraizumi in what is now southern Iwate Prefecture in the Tōhoku region of Japan.

[1] The ruins are also covered as part of the Special National Historic Site designation for neighboring Mōtsū-ji.

Both Mōtsū-ji and Kanjizaiō-in also had large earthen walls surrounding their compounds with majestic entrance gates.

Both Mōtsū-ji and Kanjizaiō-in were destroyed by fire in 1198 following the downfall of the Northern Fujiwara dynasty, although a smaller temple may have continued to exist on this site until 1578.

The temple was described in detail in the Kamakura period chronicle, Azuma Kagami, and the foundation pillars of many of the building described have been located.