A floating structure comprising: a main body including leg wells; legs penetrating the leg wells and having cords and racks; at least one jacking unit generating a lifting force to move the legs and the main body in the vertical direction relatively; and a unit installation means coupled with the main body to position the jacking unit in the main body, wherein the unit installation means comprises: a case installation unit disposed to correspond to the cords and the racks of the legs along the inner walls of the leg wells; and a jack case installed in the case installation unit to accommodate the jacking unit to move the legs in the vertical direction, the floating structure being characterized in that: the jack case is positioned in the case installation unit to prevent protrusion above the main deck of the main body and includes a housing in which the jacking unit is positioned; wherein the housing comprises: a bottom plate having passing recesses through which the cords, the racks, and an end of a brace of the legs pass vertically; lateral plates protruded from both sides of the bottom plate; an upper plate connecting upper ends of the lateral plates to each other and having the same passing recesses as the passing recesses of the bottom plate; a pair of front plates (1125A, 1125B) connecting the lateral plates, the bottom plate, and front ends of the upper plates and spaced apart from each other by a distance such that the cords of the legs, the racks, and the end of the brace may pass therethrough in the vertical direction; a rear plate separately coupled to rear ends of the lateral plates, the bottom plate, and the upper plate; and bulkheads spaced apart from the front plates (1125A, 1125B) in parallel, connected between the lateral plates, and having installation holes of the same size as those of the jacking unit and the unit housing to insert the jacking unit thereinto; and finishing plates connected between the bulkheads and the front plates (1125A, 1125B) around the installation holes. a main body including leg wells; legs penetrating the leg wells and having cords and racks; at least one jacking unit generating a lifting force to move the legs and the main body in the vertical direction relatively; and a unit installation means coupled with the main body to position the jacking unit in the main body, wherein the unit installation means comprises: a case installation unit disposed to correspond to the cords and the racks of the legs along the inner walls of the leg wells; and a jack case installed in the case installation unit to accommodate the jacking unit to move the legs in the vertical direction, the floating structure being characterized in that: a case installation unit disposed to correspond to the cords and the racks of the legs along the inner walls of the leg wells; and a jack case installed in the case installation unit to accommodate the jacking unit to move the legs in the vertical direction, the floating structure being characterized in that: the jack case is positioned in the case installation unit to prevent protrusion above the main deck of the main body and includes a housing in which the jacking unit is positioned; wherein the housing comprises: a bottom plate having passing recesses through which the cords, the racks, and an end of a brace of the legs pass vertically; lateral plates protruded from both sides of the bottom plate; an upper plate connecting upper ends of the lateral plates to each other and having the same passing recesses as the passing recesses of the bottom plate; a pair of front plates (1125A, 1125B) connecting the lateral plates, the bottom plate, and front ends of the upper plates and spaced apart from each other by a distance such that the cords of the legs, the racks, and the end of the brace may pass therethrough in the vertical direction; a rear plate separately coupled to rear ends of the lateral plates, the bottom plate, and the upper plate; and bulkheads spaced apart from the front plates (1125A, 1125B) in parallel, connected between the lateral plates, and having installation holes of the same size as those of the jacking unit and the unit housing to insert the jacking unit thereinto; and finishing plates connected between the bulkheads and the front plates (1125A, 1125B) around the installation holes. a bottom plate having passing recesses through which the cords, the racks, and an end of a brace of the legs pass vertically; lateral plates protruded from both sides of the bottom plate; an upper plate connecting upper ends of the lateral plates to each other and having the same passing recesses as the passing recesses of the bottom plate; a pair of front plates (1125A, 1125B) connecting the lateral plates, the bottom plate, and front ends of the upper plates and spaced apart from each other by a distance such that the cords of the legs, the racks, and the end of the brace may pass therethrough in the vertical direction; a rear plate separately coupled to rear ends of the lateral plates, the bottom plate, and the upper plate; and bulkheads spaced apart from the front plates (1125A, 1125B) in parallel, connected between the lateral plates, and having installation holes of the same size as those of the jacking unit and the unit housing to insert the jacking unit thereinto; and finishing plates connected between the bulkheads and the front plates (1125A, 1125B) around the installation holes.