A connecting device includes a first flexible printed circuit including a bonding end in which a plurality of connecting pads are provided, a first base portion, a junction portion extending between the bonding end and the first base portion, and a plurality of traces extending from the first base portion to the bonding end, a first connector that is mounted on the first base portion, a second flexible printed circuit including a bonding end in which a plurality of connecting pads are provided, a second base portion, a junction portion extending between the bonding end and the second base portion, and a plurality of traces extending from the second base portion to the bonding end, and a second connector that is mounted on the second base portion. The first connector and the second connector are disposed side by side in a same plane.