There are provided an ice thermal storage tank having excellent cold water generation efficiency and having a considerably reduced size, and a water cooler having the same. The ice thermal storage tank includes: a tank body accommodating an ice storage liquid cooled according to an ice thermal storage scheme; a cold water generation unit heat-exchanging introduced water with the cooled ice storage liquid to generate cold water; and a circulation unit extracting the ice storage liquid accommodated in the tank body to circulate it within the tank body. The water cooler includes: the thermal storage tank cooling water supplied from the outside; and a water dispensing unit dispensing cooled water from the ice thermal storage tank. Since an ice storage liquid is circulated without using a stirrer, the size of an ice thermal storage tank can be remarkably reduced, and thus, a water cooler is reduced in size.