An electronic modulating device is provided. The electronic modulating device includes a substrate, a plurality of first electrodes, a plurality of second electrodes and a third electrode. The plurality of first electrodes are disposed on the substrate. The plurality of second electrodes are disposed on the substrate. The third electrode is disposed on the plurality of first electrodes and the plurality of second electrodes, and includes a plurality of openings. The electronic modulating device is an antenna device. One of the plurality of openings is disposed corresponding to one of the plurality of first electrodes, and an area of the one of the plurality of openings is different from an area of another one of the plurality of openings.