Provided is a method for manufacturing a floating structure of a MEMS. The method for manufacturing a floating structure of a microelectromechanical system (MEMS), comprising the steps of: a) forming a sacrificial layer including a thin layer pattern doped with impurities on a substrate; b) forming a support layer on the sacrificial layer; c) forming a structure to be floated on the support layer by using a subsequent process; d) forming an etch hole exposing both side portions of the thin layer pattern; and e) removing the sacrificial layer through the etch hole to form an air gap between the support layer and the substrate.