A shielded flat cable includes a first differential signal line pair including mutually parallel first and second signal lines, first and second ground lines parallel to the first differential signal line pair arranged between the first and second ground lines, an insulating layer covering the first differential signal line pair, the first and second ground lines, a first shielding layer covering a first surface of the insulating layer, and a second shielding layer covering a second surface of the insulating layer, opposite to the first surface. The insulating layer includes an opening exposing the first ground line at the first surface of the insulating layer, and the first shielding layer is electrically connected to the first ground line through the opening. A width of the first ground line is greater than a width of each of the first and second signal lines.