Jens Ågessøn Bjelke (2 February 1580 – 7 November 1659) was a Norwegian nobleman, who was Chancellor of Norway from 1614 to 1648, when he was succeeded by Hannibal Sehested. He was the son of Åge Bjelke and Margrethe Thott. At the time of his death, he was Norway's largest land owner. After his tenure as Chancellor, the office largely lost its influence and was abolished in 1679.
Bjelke was born at Austrått. At 20 years of age, he was sent abroad to study, studying in , of Leipzig, Leiden and elsewhere. He studied medicine, among other things. On his return on 20 February 1605 he was employed at the Danish Chancery and remained there as a secretary until 20 January 1609. During this time he was assigned the prosecution of the case against Jørgen Dybvad in 1607. He also continued his pursuit of literary works and wrote "Regarding Greenland" on the occasion of expeditions to rediscover that country.
When he terminated work at the chancery and was proceeding to Norway, he accompanied Christian Friis to the Danish Council meeting in Horsens, in late January 1609, addressing Sweden's continuing attempts to penetrate into Northern Norway Nordland and Finnmark. From Horsens, he served as courier to convey the letters directing the men governing these northern Norwegian territories.
Upon his return to Norway, he resided at Austrått, which he had inherited from his father, who died in 1603. Austrått was a setegård or noble-seat farm, which was therefore exempt from taxes and tithe.
In 1610 he married Sophie Brockenhuus (who died 1656). She brought substantial land to the marriage, including Elingård and Sande farms in Smaalenene, Hovinsholm farm in Hedemarken and Kanestrøm farm at Nordmøre, as well as the allodial rights to Evje farm in Smaalenene. With this marriage, he became one of the wealthiest nobles in Norway. Later he bought Storfosna farm (another setegård) and Tøndel farms near Austrått, Holden farm in Nordmøre, Mel and Hatteberg farms (now Rosendal) in Sunnhordland, Skredshol farm in Hedemarken, Toyen farm near Christiania, and Kjølberg, Veden and Herrebrøden farms in Smaalenene. By the time of his death, he was the largest landowner in Norway.