A cable assembly includes a cable, a connector that is provided at an end of the cable in a direction in which the cable extends, a plurality of electric transmission lines configured to transmit an electric signal, and a plurality of optical transmission lines configured to transmit an optical signal. The plurality of electric transmission lines and the plurality of optical transmission lines are provided in the cable assembly so as to extend across the cable and the connector. The plurality of optical transmission lines are provided so that at least one of the plurality of optical transmission lines is provided at each of ends of the cable assembly in a width direction perpendicular to the direction in which the cable extends. The plurality of electric transmission lines are provided inside the plurality of optical transmission lines in the width direction.