A cable structure includes isolation layers, a first signal wire, a second signal wire, a first ground wire, a second ground wire, a first conductor, and a second conductor. These signal and ground wires are parallel along a first direction and between the isolation layers. These signal wires are adjacent, and the ground wires are respectively at outer sides of these signal wires. The first conductor is on at least one of the isolation layers along a second direction orthogonal to the first direction and is electrically connected to the first and second ground wires. The second conductor is on an outer surface of at least one of the second isolation layers along the first direction and is electrically connected to the first conductor. The second conductor is symmetrical based on a central line between the first and second signal wires.