The invention provides an Al-base alloy wiring material which, in a display device comprising a thin film transistor, can realize direct junction also to a semiconductor layer such as an n<+>-Si layer. The Al-base alloy wiring material comprises nickel and boron incorporated in aluminum and is characterized by further comprising nitrogen (N). The nitrogen content is preferably not less than 2*10<17> atoms/cm<3> but less than 9*10<21> atoms/cm<3>. When the composition proportion of nickel is x atomic percent, the composition proportion of boron is y atomic percent, the composition proportion of aluminum is z atomic percent, and x+y+z=100, preferably, x is not less than 0.5 but not more than 10.0, y is not less than 0.05 but not more than 11.00, y+0.25x is not less than 1.00, y+1.15x is not more than 11.50, and the rest contains nitrogen.