To provide a flexible flat cable which can have contacting points to connectors formed on its one surface and remove the cause of interfering factors to impedance, while improving shielding capacity.

The flexible flat cable is a flexible insulator sheet 2, one side of which is installed with the primary conductive pattern P1 and the other side of which with the secondary conductive pattern P2. The primary conductive pattern P1 comprises a plurality of patterns 3's, each containing a signal pattern S and two ground patterns G's placed on both sides of S, which are extended along the lengthwise direction of the flexible flat cable 2. The secondary conductive pattern P2 comprises a plurality of conductive patterns 5's which are extended along the lengthwise direction of the insulating sheet 2. Each conductive pattern 5 is arranged in a position facing each pattern group 3 sandwiching the insulating sheet 2 between.