A method of manufacturing an active matrix substrate prevents an increase in the number of production steps while simultaneously preventing electrostatic discharge at a TFT channel. The method preferably includes the steps of forming a short-circuit wiring for connecting a data signal line or a source electrode to a drain electrode or a drain side circuit; successively forming an upper insulating film having an opening for short-circuit wiring separation and a transparent conductive film at a region above the short-circuit wiring as upper layers of the short-circuit wiring; and removing at least the transparent conductive film inside the opening for short-circuit wiring separation and the short-circuit wiring below the opening for short-circuit wiring separation to perform patterning of the pixel electrode and separation of the short-circuit wiring in the same step.