A manufacturing method of a flat shield cable has a step of arranging a plurality of flat conductors including a ground line parallel with each other in one plane at a pitch P, a step of forming a flat cable by laminating a first insulating film on the flat conductors from both sides of an arrangement plane of the flat conductors, a step of laminating a shield layer on outside surfaces of the flat cable, and a step of electrically connecting the ground line to the shield layer. The manufacturing method further has a step of cutting the ground line at a portion other than in the conductor exposure portions and folding cutting portions of the ground line to outside the first insulating film before laminating the shield layer, and a step of electrically connecting only the folded ground line among the flat conductors to the shield layer.