Abstract: A flat bundle of cables are each sheathed with an electrically insulative synthetic resin and arranged in a spaced relationship while extending in parallel with each other. A plurality of baseless bulbs are arranged one after another along at least one cable of the flat bundle of cables while making electrical connection to the at least one cable via lead wires. A plurality of moldable plastic material holding structures are arranged one after another in the spaced relationship along the flat bundle of cables. Each holding structure serves to firmly hold a respective baseless bulb and the flat bundle of cables so that a central axis of the bulb extends parallel with a plane of the flat bundle of cables and perpendicular to the extending direction of the cables.