Järvafältet nature reserve, Nature reserve in Järfälla and Sollentuna Municipalities, Sweden.

Järvafältet nature reserve consists of two parts: Östra Järvafältets naturreservat in Sollentuna, 1,016 hectares (985 land), and Västra Järvafältets naturreservat in Järfälla, 700 hectares (609 land). It holds three lakes, Ravalen, Säbysjön and Översjön, plus the overgrown wetlands Djupan and Kalkviken, spruce forest, rocky outcrops, mixed woodland and oak slopes. Trails include Järvaleden (35 km), Milspåret (10 km) and Ravalnspåret (2.7 km).

The area has been settled since around 500 BC, with Bronze Age remains also recorded. Larger ancient monument areas lie at Säby gård and at Bögs and Väsby gårdar, and a rune slab stands at Säby gård. In 1905 the whole Järvafältet became a military training ground; activity wound down from 1960, and because the area was closed to the public until 1962 the old farms and their surroundings survived.

At Väsby gård there is a naturskola and Floras trädgård, and Bögs gård serves as a display farm where the old cultivated landscape is kept open, partly with traditional methods. Säby gård, with a rune slab nearby, now operates as a värdshus, while Hägerstalunds gård has become a conference facility.

Main entrances are at Bögs gård on the Sollentuna side and Säby gård just east of Jakobsberg's centre, both with car parks; roads inside are closed by barriers. Marked routes include the 35 km Järvaleden, the 10 km Milspåret and the 2.7 km Ravalnspåret, plus prepared exercise tracks and bridle paths.

The reserve's open farmland around Bögs gård and Väsby gård is still grazed and mown with traditional methods, keeping the old cultivated landscape open. At Väsby gård there is a nature school and Floras trädgård, a garden used in that work. The two former lakes Djupan and Kalkviken have almost overgrown into wetlands.