Ashigarashimo District is a district located in western Kanagawa Prefecture, Japan. It is characterized as one of the most sparsely populated mountainous districts in the region. A significant portion of its territory falls within the boundaries of Fuji-Hakone-Izu National Park. The district serves as an administrative division within the prefecture, encompassing several towns and villages.

The area originated as Ashinoshimo District, one of the ancient subdivisions of Sagami Province under the Nara period Ritsuryō system. During the Sengoku period, it was controlled by the Hōjō clan, and later became part of Odawara Domain in the Edo period. Some land was held as tenryō territory administered by the Tokugawa shogunate due to disasters from Mount Fuji eruptions.

Following the Meiji Restoration, the area formed part of Ashigara Prefecture before becoming a district of Kanagawa in 1878. In 1889, it was divided into two towns and thirty villages. The city of Odawara, whose majority area was formerly part of the district, was elevated to city status in 1940. The district currently includes the towns of Hakone, Manazuru, and Yugawara.

The region offers access to natural landscapes within Fuji-Hakone-Izu National Park. Historical sites reflect its past under the Hōjō clan and Tokugawa shogunate. The area retains cultural connections to its origins as a subdivision of Sagami Province. Visitors can explore the mountainous terrain and historical remnants associated with the Edo period domain structures.

As of 2009, the district had an estimated population of 48,713 people. The total area was 140.73 km2, resulting in a density of 346 persons per km2. Local voters rejected a planned merger of Yugawara into Odawara in a 2005 referendum following a 2004 vote. The district remains a distinct administrative entity within Kanagawa Prefecture.