[Summary] There is provided a cryogenic tank 100 having a dual construction for storing ultralow temperature, liquid with improvement which allows simplicity in its construction, and headiness of setup and allows reduction in the setup, yet achieves high reliability. For accomplishing the above-noted object, in a cryogenic tank 100 having a dual construction with ain inner tank 3 for storing low-temperature liquefaction fluid L therein and an outer tank 6 enclosing the bottom and the shell of the inner tank 3. The inner tank 3 includes a bottomed inner vessel 1 formed of concrete and an inner cold resistant relief 2 covering the inner face of the inner vessel 1. The outer tank 6 includes a bottomed outer vessel, 4 formed oaf concrete, and an outer cold resistant relief 5 covering the inner face of the outer vessel 4.