A MEMS device is provided. The MEMS device includes a substrate having at least one contact, a first dielectric layer disposed on the substrate, at least one metal layer disposed on the first dielectric layer, a second dielectric layer disposed on the first dielectric layer and the metal layer and having a recess structure, and a structure layer disposed on the second dielectric layer and having an opening. The opening is disposed on and corresponds to the recess structure, and the cross-sectional area at the bottom of the opening is smaller than the cross-sectional area at the top of the recess structure. The MEMS device also includes a sealing layer, and at least a portion of the sealing layer is disposed in the opening and the recess structure. The second dielectric layer, the structure layer, and the sealing layer define a chamber.