 form of the manufacturing method of an active matrix substrate according to the present invention includes following processes: A first conductive film consisting of one conductive material is patterned to form a first conductive film pattern on an insulating substrate, and depositing in order an insulation layer, a semiconductor thin film, a semiconductor thin film for ohmic contact, and a second conductive film consisting of other conductive material to form laminated films on the insulating substrate and the first conductive film pattern. After that, a resist pattern having a second portion with a opening therein and a first portion thicker than the first portion is formed on the second conductive film and etching the laminated films by using the resist pattern as an etching mask to form a contact hole reaching a surface of the first conductive film pattern. Subsequently, the second portion of the resist pattern is removed by etching the resist pattern to make the first portion of the resist pattern remain as xe0x00x0ca first portion left,xe0x00x0d and the second conductive film, the semiconductor thin film for ohmic contact and the semiconductor thin film are etched by using the first portion left as an etching mask to form a 