The (Roman Catholic) Archdiocese of Thare and Nonseng (Archidioecesis Tharensis et Nonsengensis; Thai: อัครสังฆมณฑลท่าแร่-หนองแสง, RTGS: Akkhrasangkhamonthon Tha Rae-Nong Saeng) is located in the north-east of Thailand.

It is based in Tha Rae, a subdistrict municipality (thesaban tambon) in the Mueang Sakon Nakhon district.

In 1938 the northern part was split off to create the Prefecture Apostolic of Vientiane and Luang-Prabang.

The St. Michael the Archangel Cathedral is located in Ban Tha Rae, Tha Rae subdistrict, Mueang Sakon Nakhon district, at the northern shore of the Nong Han Lake, 17°15′15″N 104°11′3″E / 17.25417°N 104.18417°E / 17.25417; 104.18417.

Before Thare and Nonseng became a diocese, the administrator had the title vicar, but was also a titular bishop.