A solid-state imaging device includes a pixel array section and a signal processing section. The pixel array section is configured to include a plurality of arranged rectangular pixels, each of which has different sizes in the vertical and horizontal directions, and a plurality of adjacent ones of which are combined to form a square pixel having the same size in the vertical and horizontal directions. The signal processing section is configured to perform a process of outputting, as a single signal, a plurality of signals read out from the combined plurality of rectangular pixels.