An electro-optical device substrate includes a substrate, a plurality of data lines, a plurality of scanning lines, pixel electrodes, and transistors. The plurality of data lines and the plurality of scanning lines intersect with each other in a display area formed on the substrate. The pixel electrodes are provided at positions corresponding to intersections of the plurality of data lines and the plurality of scanning lines. Each of the transistors includes a semiconductor layer and a gate electrode. The semiconductor layer has a channel region, a data line side source/drain region, a pixel electrode side source/drain region, a first junction region, and a second junction region. The channel region has a channel length along a first direction in the display area. The data line side source/drain region is electrically connected to a corresponding data line. The pixel electrode side source/drain region is electrically connected to a corresponding pixel electrode.