An electro-optical device includes an element substrate having a plurality of pixel regions; thin-film transistors, arranged in the pixel regions, including gate electrodes, portions of a gate insulating layer, and semiconductor layers; pixel electrodes electrically connected to drain regions of the thin-film transistors; and storage capacitors including lower electrodes and upper electrodes that are opposed to the lower electrodes with insulating layers disposed therebetween, the insulating layers being made of the same material as that for forming the gate insulating layer. The upper electrodes overlap with some of end portions of the lower electrodes. The gate insulating layer has thin portions located in inner portions of regions overlapping with the lower and upper electrodes and thick portions which are located in regions overlapping with the upper electrodes and the end portions of the lower electrodes and which have a thickness greater than that of the thin portions.