A mother substrate includes a display substrate cell defined by a scribe line, the display substrate cell including a plurality of gate lines, a gate circuit part driving the gate lines, and a gate pad part connected to the gate circuit part, a gate test pad part in a peripheral area surrounding the display substrate cell, the gate test pad part being configured to receive a gate test signal, a gate test line part connecting the gate test pad part and the gate pad part, and a switching part connected to the gate test line part and configured to control turning on and turning off of the gate test line part.