Zhamantuz () is a salt lake in the Aksu City Administration, Pavlodar Region, Kazakhstan.
The lake lies to the southwest of Aksu city. The area surrounding the lake is used for livestock grazing in the spring.
Zhamantuz is an endorheic lake of the northern end of the Kazakh Uplands. It lies at an elevation of . The Irtysh flows to the east of the eastern shores of the lake.
There are a number of lakes in its vicinity, such as Kudaikol to the northwest, Altybaysor to the southeast and Kalkaman, to the northeast.