An oxide semiconductor film and an oxide conductive film are stacked to form a semiconductor layer. The oxide conductive film is made of a material by which the oxide conductive film is etched at a higher speed than the oxide semiconductor film for example with a PAN chemical containing phosphoric acid, nitric acid, and acetic acid. A source electrode and a drain electrode are electrically connected to the oxide semiconductor film through the oxide conductive film at least at an end portion of the source electrode and an end portion of the drain electrode facing each other. A channel region made of the oxide semiconductor film is formed between the source electrode and the drain electrode. The oxide semiconductor film has a substantially tapered shape in cross section at an end face thereof.