Disclosed is a flat signal transmission cable with bundling structure, including at least one flexible circuit. The flexible circuit includes a plurality of clustered flat cable components that are formed by slitting in a direction parallel to extension direction of the flexible circuit to impose free and independent flexibility for bending to each clustered flat cable component. At least one bundling structure is formed on a lateral side edge of a predetermined clustered flat cable component of the cluster section of the flexible circuit. The bundling structure forms a fastening section. When the clustered flat cable components of the cluster section of the flexible circuit are stacked to form a bundled structure, the bundling structure bundles the plurality of clustered flat cable components and is secured by being fastened by the fastening section.