The present disclosure relates to a method of constructing a liquefied gas storage tank on land, which enables rapid and easy construction of walls of a cylindrical storage tank by stacking a plurality of pre-produced unit-wall structures to be stacked or superposed with respect to one another. The method includes: producing unit-wall structures made of concrete and each having iron rods arranged lengthwise and breadthwise therein, stacking the unit-wall structures in a cylindrical arrangement, and connecting the unit-wall structures adjacent and in longitudinal and lateral directions with respect to each other to form a wall of the storage tank.