To realize a high performance display at a low cost and a high mounting yield of the driving circuit. An electro-optical device according to the present invention comprises an element substrate having a plurality of pixels and a plurality of data lines electrically connected to the plurality of pixels, a circuit substrate piece mounted on the element substrate and having a first circuit which is connected to the plurality of data lines and has a plurality of thin film transistors, and an integrated circuit mounted on the circuit substrate piece and having a second circuit which is connected to the first circuit for driving the plurality of pixels via the first circuit and the plurality of data lines.