Kostroma Oblast is a federal subject of Russia. Its administrative center is the city of Kostroma and its population as of the 2021 Census is 580,976. It was formed in 1944 on the territory detached from neighboring Yaroslavl Oblast.

Kostroma is a historic city and the administrative center of Kostroma Oblast, Russia. A part of the Golden Ring of Russian cities, it is located at the confluence of the rivers Volga and Kostroma. In the 2021 census, the population is 267,481.