A method of forming a floating structure lifting up from a substrate and a method of manufacturing a field emission device (FED) employing the floating structure are provided. The method of forming a floating structure includes forming an expansion causer layer, which can generate a byproduct from the reacting with a predetermined reactant gas causing volume expansion, on the substrate; forming an object material layer for the floating structure on a resultant stack; forming a hole through which the reactant gas is supplied on a resultant stack; supplying the reactant gas through the hole so that the object material layer partially lifts up from the substrate due to the byproduct generated from the reaction of the expansion causer layer with the reactant gas; and removing the byproduct through the hole so that the portion of the object material layer lifting up from the substrate can be completely separated from the substrate to form the floating structure.