The present disclosure relates to a unit-wall structure (10) for a liquefied gas storage tank on land, which enables rapid and easy construction of a cylindrical wall of the storage tank by stacking a plurality of pre-produced unit-wall structures to overlap one another. The unit-wall structure (10) includes iron rods (11) arranged lengthwise and breadthwise therein, wherein the unit-wall structure has an arc shape so that a plurality of unit-wall structures are stacked to form a cylindrical wall of the storage tank.