Ruzayevka is a town located in the Republic of Mordovia, Russia. It is situated on the Insar River, approximately 25 kilometers (16 miles) southwest of the regional center, Saransk.
According to census data, the population of Ruzayevka has seen a gradual decline over recent decades. The population was recorded at 51,034 during the 1989 Soviet census, decreasing to 49,790 in 2002 and further down to 47,523 by the 2010 census.