A liquid crystal display device comprising: a first insulation substrate and a second insulation substrate and a liquid crystal material therebetween; scanning signal lines over a surface of the first insulation substrate on the liquid-crystal-material side; a first insulation layer over the scanning signal lines and on the surface of the first insulation substrate on the liquid-crystal-material side; a semiconductor layer and pixel electrodes over the surface of the first insulation layer on the liquid-crystal-material side; and a second insulation layer between the pixel electrodes and a common electrode, wherein the liquid crystal display device further comprises: video signal lines and source electrodes, characterized in that a metal layer is stacked on a surface of the semiconductor layer on a liquid-crystal-material side; each source electrode is constituted of a portion of the metal layer arranged on a surface of a portion of the semiconductor layer on the liquid-crystal-material side which forms part of a thin film transistor, said stacked portion of the semiconductor layer and the metal layer overlaps an upper surface of the corresponding pixel electrode on the liquid-crystal-material side; the video signal lines are each constituted of stacked portions of the metal layer and the semiconductor layer being connected to drain electrodes each of which is constituted of a portion of the metal layer and a portion of the semiconductor layer forming part of a thin film transistor; contact holes in the second insulation layer are arranged over a surface of each pixel electrode on the liquid-crystal-material side joining a surface of the corresponding source electrode on the liquid-crystal-material side; and a conductive film is made of ITO and extends over the contact holes so that corresponding pixel electrodes and source electrodes are connected with each other in a conductive state. a first insulation substrate and a second insulation substrate and a liquid crystal material therebetween; scanning signal lines over a surface of the first insulation substrate on the liquid-crystal-material side; a first insulation layer over the scanning signal lines and on the surface of the first insulation substrate on the liquid-crystal-material side; a semiconductor layer and pixel electrodes over the surface of the first insulation layer on the liquid-crystal-material side; and a second insulation layer between the pixel electrodes and a common electrode, wherein the liquid crystal display device further comprises: video signal lines and source electrodes, characterized in that a metal layer is stacked on a surface of the semiconductor layer on a liquid-crystal-material side; each source electrode is constituted of a portion of the metal layer arranged on a surface of a portion of the semiconductor layer on the liquid-crystal-material side which forms part of a thin film transistor, said stacked portion of the semiconductor layer and the metal layer overlaps an upper surface of the corresponding pixel electrode on the liquid-crystal-material side; the video signal lines are each constituted of stacked portions of the metal layer and the semiconductor layer being connected to drain electrodes each of which is constituted of a portion of the metal layer and a portion of the semiconductor layer forming part of a thin film transistor; contact holes in the second insulation layer are arranged over a surface of each pixel electrode on the liquid-crystal-material side joining a surface of the corresponding source electrode on the liquid-crystal-material side; and a conductive film is made of ITO and extends over the contact holes so that corresponding pixel electrodes and source electrodes are connected with each other in a conductive state. video signal lines and source electrodes, characterized in that a metal layer is stacked on a surface of the semiconductor layer on a liquid-crystal-material side; each source electrode is constituted of a portion of the metal layer arranged on a surface of a portion of the semiconductor layer on the liquid-crystal-material side which forms part of a thin film transistor, said stacked portion of the semiconductor layer and the metal layer overlaps an upper surface of the corresponding pixel electrode on the liquid-crystal-material side; the video signal lines are each constituted of stacked portions of the metal layer and the semiconductor layer being connected to drain electrodes each of which is constituted of a portion of the metal layer and a portion of the semiconductor layer forming part of a thin film transistor; contact holes in the second insulation layer are arranged over a surface of each pixel electrode on the liquid-crystal-material side joining a surface of the corresponding source electrode on the liquid-crystal-material side; and a conductive film is made of ITO and extends over the contact holes so that corresponding pixel electrodes and source electrodes are connected with each other in a conductive state.