Seljord is a municipality in Telemark county, Norway. It is located in the traditional districts of Upper Telemark and Vest-Telemark. The administrative centre of the municipality is the village of Seljord. Other villages in the municipality include Flatdal and Åmotsdal.

The 715-square-kilometre (276 sq mi) municipality is the 161st largest by area out of the 356 municipalities in Norway. Seljord is the 229th most populous municipality in Norway with a population of 2,939. The municipality's population density is 4.4 inhabitants per square kilometre (11/sq mi) and its population has decreased by 0.2% over the previous 10-year period.

Seljord is famous for its sea serpent, Selma, who allegedly lives in Lake Seljord (Seljordsvatnet).

The yearly Dyrsku'n market, held since 1866, attracts 60,000 to 80,000 visitors each year. The large fair started as a show of farm animals. More recently, it also includes a huge market with vendors selling a variety of goods including base layer clothing, Bergans outdoors equipment, crafts, and food. Amusement rides are also featured.

Seljord folk high school is located in Seljord. The school offers a variety of courses including outdoor adventure, theater, music, and art.

The parish of Sillejord (later spelled Seljord) was established as a municipality on 1 January 1838 (see formannskapsdistrikt law). On 11 October 1873, an unpopulated area of Kviteseid Municipality was transferred to Seljord. On 1 January 1883, an area of southeastern Seljord (population: 235) was transferred to the neighboring Bø Municipality. On 23 January 1905, an unpopulated part of Hjartdal Municipality was transferred to Seljord.

The municipality (originally the parish) is named after the old Seljord farm (Old Norse: Seljugerði) since the first Seljord Church was built there. The first element is the genitive case of the word selja which means "sallow-tree" or "willow". The last element is gerði which means "field". Prior to 1889, the name was spelled Silgjord or Sillejord.

The coat of arms was granted on 15 September 1989. The official blazon is "Gules, a sea serpent Or" (Norwegian: På raud grunn ein gull sjøorm). This means the arms have a red field (background) and the charge is a sea serpent. The charge has a tincture of Or which means it is commonly colored yellow, but if it is made out of metal, then gold is used. The design symbolizes the local legend of a sea serpent named Selma who allegedly lives in the lake Seljordsvatn. The arms were designed by Trygve Magnus Barstad. The municipal flag has the same design as the coat of arms.

The Church of Norway has one parish (sokn) within the municipality of Seljord. It is part of the Øvre Telemark prosti (deanery) in the Diocese of Agder og Telemark.

Churches in Seljord

Parish (sokn)	Church name	Location of the church	Year built
Seljord	Flatdal Church	Flatdal	1654
	Mandal Chapel	Mandal	1954
	Seljord Church	Seljord	1180
	Åmotsdal Church	Åmotsdal	1792

Seljord Municipality is responsible for primary education (through 10th grade), outpatient health services, senior citizen services, welfare and other social services, zoning, economic development, and municipal roads and utilities. The municipality is governed by a municipal council of directly elected representatives. The mayor is indirectly elected by a vote of the municipal council. The municipality is under the jurisdiction of the Telemark District Court and the Agder Court of Appeal.

This list is incomplete; you can help by adding missing items. (August 2023)

The mayors (Norwegian: ordfører) of Seljord (incomplete list):

The municipal council (Kommunestyre) of Seljord is made up of 17 representatives that are elected to four-year terms. The tables below show the current and historical composition of the council by political party.

• 
  Memorial to Magnus Brostrup Landstad
• 
  Mandal Chapel
• 
  Åmotsdal Church
• 
  Lake Seljord (Seljordsvatnet)
• 
  Flooded boathouse in Seljord

• Anne Godlid (1773-1863), a 19th-century Norwegian storyteller
• Jacob Andreas Wille (1777–1850), a priest, teacher, and Mayor of Seljord
• Daniel Bremer Juell (1808-1855), the Bishop of Tromsø from 1849-1855
• Jørund Telnes (1845-1892), a farmer, teacher, writer, and Mayor of Seljord
• Halvor J. Sandsdalen (1911-1998), a writer and folklore collector
• Ingebjørg Kasin Sandsdalen (1915-2003), a poet
• Aslaug Høydal (1916-2007), a schoolteacher, novelist, poet, and children's writer
• Terje Grøstad (1925–2011), a painter and illustrator who lived in Flatdal
• Hallvard Flatland (born 1957), a TV personality
• Kim Leine (born 1961), a Danish-Norwegian author
• Helga Flatland (born 1984), a novelist and children's writer who was brought up in Flatdal

• The dictionary definition of Seljord at Wiktionary
• Municipal fact sheet from Statistics Norway (in Norwegian)* Telemark travel guide from Wikivoyage
• Seljord Folk High School