A multi-layer line structure including a substrate, a lower layer Cu line located on the substrate, an upper layer Cu line located on an insulating layer including an inorganic film located on the lower layer Cu line and an organic resin film located on the inorganic film, and a via connection part located in a via connection hole running in an up-down direction through the insulating layer in an area where the lower layer Cu line and the upper layer Cu line overlap each other is provided. The via connection part includes a barrier conductive layer located on a part of the lower layer Cu line exposed to a bottom part of the via connection hole and on an inner wall of the via connection hole.