Mamontovsky District (Russian: Ма́монтовский райо́н) is an administrative[1] and municipal[4] district (raion), one of the fifty-nine in Altai Krai, Russia.

The area of the district is 2,305.2 square kilometers (890.0 sq mi).

[2] Its administrative center is the rural locality (a selo) of Mamontovo.

[1] As of the 2010 Census, the total population of the district was 23,412, with the population of Mamontovo accounting for 37.5% of that number.

[3] Lakes Gorkoye and Bolshoye Ostrovnoye are located in the district.