A wiring substrate includes a first conductive film, a second conductive film disposed over the first conductive film with a first insulating film therebetween, a third conductive film disposed over the second conductive film, at a side away from the first conductive film, with a second insulating film therebetween, signal lines formed of the third conductive film, leading lines each having a first end portion connected to the signal line and a second end portion through which a signal to the signal line enters, the first and second end portions of the leading lines at least being formed of the third conductive film, and a spare line including at least first and second line overlapping portions, respectively, overlapping the first and second end portions of the leading lines, the first and second line overlapping portions being formed of the first conductive film and allow electrically connection to each other.