A flexible flat cable is provided. The FFC comprises multiple conductors with widths of 0.3(.+-.0.03)mm arranged in a parallel manner with a pitch of 0.5 (.+-.0.05)mm, the first insular material and the second insular material sandwiching these conductors from both sides, shield material, and the reinforcement board. The first insular material is porous PET possessing a 34 .mu.m thick porous layer and the shield material is a polymer-based shield material possessing a shield layer made of a polymer-based conductive layer equal to or less than 20 .mu.m thick that is a prescribed resin formed including air with uniformly dispersed conductive particles. Due to this, the FFC maintains the shield effect without damaging the electrical characteristics and also, along with being compatible with existing connecters, can combine with the electrical traits by existing processes and furthermore is capable of being established with any number of wires, any length of cable, and any alignment of wiring.