Oyaku-en (御薬園) is a medicinal herb garden in the city of Aizuwakamatsu, Fukushima Prefecture, Japan.

[2] In 1670, Hoshina Masatsune, the second daimyō of the Aizu Domain, cultivated various herbs in the garden, notably Korean ginseng.

The garden pond is named Shinji no Ike and is shaped like the kanji character for "heart" (心).

The building was used when lords, superior officials, merchants or general managers of the clan were invited to Aizu.

The Rakujutei (楽寿亭) is a tea ceremony cottage built on Naka shima or "Middle Island".