The patients, from a village in the Zhambyl Region, were hospitalized a week ago.
"Laboratory tests have confirmed the diagnosis," the emergencies ministry press service said, adding that the patients were in satisfactory condition and that people they had come into contact with were being closely watched.
Measures are being taken to prevent an epidemic in the region.
Outbreaks of anthrax are relatively common in the Central Asian state. Owners of sick cattle have been known to sell meat from infected animals after culling them, bypassing veterinary checks.
At least two people died of anthrax in Kazakhstan last summer.
Anthrax affects both wild mammals and domestic cattle that ingest or inhale the bacterial spores while grazing. Humans can contract the disease if they are exposed to the blood or tissue of infected animals.
Anthrax can be highly lethal, but in some forms responds well to antibiotic treatment.
