Irdemousa (Persian: ارديموسي) is a city in, and the capital of, Sabalan District, Sareyn County, Ardabil province, Iran. It also serves as the administrative center for Sabalan Rural District. The closest major cities include Ardabil, Tabriz, Rasht, and Zanjan.

At the 2006 census, its population was 725 in 158 households, when it was a village in Sabalan Rural District of the former Sareyn District of Ardabil County. The following census in 2011 counted 789 people in 249 households, by which time the district had been separated from the county in the establishment of Sareyn County. The latest census in 2016 showed a population of 816 people in 279 households. It was the most populous village in its rural district.

After the census, the village of Irdemousa was elevated to the status of a city.