Oyakuen was founded in the 14th Century and soon, with the encouragement of Ashina Morihisa, the local lord, became a medicinal herb garden for the community. The current landscape, meant to show nature in miniature, was designed by Meguro Jotei during the Edo period.
The garden surrounds a pond, Shinji no Ike, in the shape of the character 心 kokoro (heart), in the center of which sits the Rakujutei tea ceremony cottage. A larger tea house, Ochayagoten, adorns the near end of the pond and it was here that visiting nobles were formerly entertained.
Oyakuen was left in ruins after the Boshin war of 1868-9, but was restored to the point that it was named a nationally renowned garden in 1932.