A method of manufacturing a semiconductor device includes: preparing a wafer in which a first cell area and a second cell area are defined; forming a bottom electrode structure in the first cell area and a dummy structure located in the second cell area; and sequentially forming a dielectric layer and a top electrode on the bottom electrode structure and the dummy structure, wherein the bottom electrode structure includes a plurality of bottom electrodes extending in a first direction in the first cell area and first and second supporters to support the plurality of bottom electrodes, wherein the dummy structure includes a first mold film, a first supporter film, a second mold film, and a second supporter film that are sequentially formed to cover the second cell area, and the second supporter and the second supporter film are at a same level relative to the wafer.