Abstract: A thin film transistor (TFT) matrix substrate has a testing circuit that can accurately detect the breaks in gate lines and data lines. In a substrate, TFTs are provided to be connected at the intersections of the gate lines and the data lines. A first shorting bar is commonly connected to the gate lines and a second shorting bar is commonly connected to the data lines. A first test pad receives a first test signal to be applied to the first shorting bar and a second test pad receives a first test signal to be applied to the second shorting bar. A third shorting bar is commonly connected to static electricity preventing devices installed at the gate lines and a fourth shorting bar is commonly connected to static electricity preventing devices installed at the data lines. A third test pad allows the second test signal to be applied to the third and fourth shorting during driving testing if the gate lines and the data lines have breaks or damaged.