The present invention provides the substrate for a display device, comprising a scan line, a signal line and a switching element on an insulating substrate, and further comprising an interlayer insulation film and a pixel electrode, the switching element is provided at an intersection of the scan line and the signal line, and have a gate electrode connected to the scan line, a source electrode connected to the signal line, and a drain electrode connected to the pixel electrode, the interlayer insulation film has a contact hole for connecting the drain electrode of the switching element to the pixel electrode, and a protective layer is provided above the scan line and/or the signal line in the substrate for a display device.