A method for forming a structure formed by etching which is typified by a contact hole in the semiconductor and a method for manufacturing a display device using the structure. The etching method includes at least, forming an organic mask having a first opening portion and a second opening portion by patterning an organic film which includes either one of an organic film and a film with the addition of organic solvent and is located on a constituent part to be etched, and forming a transformed organic mask by dissolving the organic mask in contact with organic solvent and reflowing.