A method of manufacturing an active matrix substrate that enables increased productivity due to a reduction in the number of patterning processes and low generation of particles during the patterning processes. The method includes forming a patterned electrode on a substrate, and covering the first electrode with an insulating film. A mono-crystalline semiconductor layer is then formed on the insulating film by attaching a first layer formed on a surface of a semiconductor wafer to the first insulating film, and peeling off a portion of the semiconductor wafer. The semiconductor layer is then patterned and doped, in part, by utilizing the patterned electrode as a photo mask for light illuminated from a lower side of the substrate. This results in part in mono-crystalline active layers for thin film transistors, which are then configured to form a pixel for an active matrix substrate.