The Nara Basin (奈良盆地 Nara-bonchi), also known as the Yamato Basin (大和盆地 Yamato-bonchi), is a valley in the north-western part of Nara Prefecture, Japan. It has an area of roughly 300 square kilometres (120 sq mi). It is surrounded on four sides by mountains: the Yamato Plateau in the east, the Ikoma-Kongō range in the west, the Narayama Hills in the north (which separate it from the Kyoto Basin), and the Ryūmon Mountains in the south.
The valley itself makes up only around 8% of the land area of Nara Prefecture, but the terrain is especially fit for rice production, and as the site of the ancient capital of Heijō-kyō it served as a political and cultural centre. Today it is closely connected to the Keihanshin metropolitan area by a strong transport infrastructure, with several major cities growing up in the area in addition to the prefectural capital Nara, and is the most densely-populated region of the prefecture.