Zhamantuz (Kazakh: Жамантұз) is a salt lake in the Zhangeldi District, Kostanay Region, Kazakhstan.

The name Zhamantuz, meaning "bad salt" in the Kazakh language, is of nomadic origin.

[1] Zhamantuz has an elongated shape, stretching for over 5 kilometers (3.1 mi) in a northeast–southwest direction.

The lake fills yearly with rain and snow and rarely freezes in the winter.

Typha and Phragmites reeds grow in stretches of the lakeshore and wormwood tufts close around the basin.