Arzamassky District is an administrative district (raion), one of the forty in Nizhny Novgorod Oblast, Russia. Municipally, it is incorporated as Arzamassky Municipal District. It is located in the southern central part of the oblast. The area of the district is 2,016.9 square kilometers (778.7 sq mi). Its administrative center is the city of Arzamas. Population: 43,723 ; 46,086 (2002 Census); 54,491 (1989 Soviet census).