A detecting device comprising: a plurality of detection electrodes extending in a first direction along a substrate and disposed apart from each other in a second direction orthogonal to the first direction; and a plurality of dummy electrodes provided between the detection electrodes, wherein the detection electrodes have a plurality of openings, the openings of the detection electrodes are arrayed in a triangular grid, the dummy electrodes are arrayed in a triangular grid, an end of each of the detection electrodes in the second direction has: a plurality of recesses; and a plurality of protrusions.