Ōmura Domain (大村藩) was a Japanese domain of the Edo period. It is associated with Hizen Province in modern-day Saga Prefecture.

Hizen Province was an old province of Japan in the area of the Saga and Nagasaki prefectures. It was sometimes called Hishū (肥州), with Higo Province. Hizen bordered on the provinces of Chikuzen and Chikugo. The province was included in Saikaidō. It did not include the regions of Tsushima and Iki that are now part of modern Nagasaki Prefecture.