Nias Regency is a regency in North Sumatra province, Indonesia; it lies on the east side of Nias Island. The regency originally covered the entire island, but was reduced to the northern half, with an area of 3,495.39 square kilometres, following the creation of the new regency of Nias Selatan on 25 February 2003. It was further reduced by the creation of the new regencies of North Nias (Kabupaten Nias Utara)and West Nias (Kabupaten Nias Barat) and the independent municipality of Gunungsitoli from other parts of Nias Regency on 29 October 2008. Since the separation of the new regencies and municipality, the reduced Regency now covers 853.44 km of land in the eastern part of the island (partly surrounding the coastal city of Gunungsitoli), and had a population of 131,377 at the 2010 Census and 146,672 at the 2020 Census; the official estimate as at mid 2023 was 146,895. Its seat is the town of Gido.

The regency was previously divided administratively into 32 districts (kecamatan). However, following the creation on 29 October 2008 of the new North Nias Regency, West Nias Regency and the newly independent city of Gunungsitoli, the residual Nias Regency was composed of only nine districts, although a tenth district (Sogaeadu) was created in 2012 from part of Gido district. These districts are tabulated below with their areas (in km) and their 2010 Census and 2020 Census populations, together with the official estimates as at mid 2023. The table also includes the locations of the district administrative centres, the number of administrative villages (all classed as rural desa) in each district, and its postal code.

Kode Wilayah	Name of District (kecamatan)	Area in km	Pop'n Census 2010	Pop'n Census 2020	Pop'n Estimate mid 2023	Admin centre	No. of villages	Post code
12.04.10	Idanogawo	138.66	25,675	26,967	27,235	Tetehosi	28	22872
12.04.11	Bawolato	204.46	22,965	25,113	25,372	Sisarahili Bawolato	25	22876
12.04.27	Ulugawo	65.97	9,740	10,191	10,099	Holi	14	22861
12.04.06	Gido	110.06	31,660	23,326	23,965	Hiliweto	21	22871
12.04.35	Sogae'adu	41.27		11,749	11,491	Sogae'adu	11	22871
12/04.28	Ma'u	61.19	9,424	10,584	10,234	Lasara Siwalubanua	11	22855
12.04.29	Somolo-molo	44.85	6,162	6,558	6,428	Somolo-molo	11	22871
12.04.05	Hiliduho	65.08	9,126	9,830	9,953	Hiliduho	16	22854
12.04.20	Hiliserangkai	61.92	7,583	12,676	12,563	Dahadano Botombawo	15	22850
12.04.21	Botomuzoi	59.98	9,042	9,678	9,555	Hiliwa'ele I	18	22815
	Totals	853.44	131,377	146,672	146,895	Gido	170

Note: (a) the population of Songaeadu District in 2010 is included with the figure for Gido District (from which it was split in 2012).

0°46′12″N 97°45′00″E / 0.7700°N 97.7500°E / 0.7700; 97.7500