An organic thin-film transistor (TFT) with a large carrier mobility includes a drain electrode, a source electrode, which are made of different materials, and a semiconductor layer formed on upper surface of a substrate. Equipment for manufacturing the organic TFT comprises a substrate mounting unit, a painting unit, a light irradiating unit, a sealed container for housing the above units, and a gas supplying unit of an antioxidant gas to the sealed container. The organic TFT to be manufactured is placed on the substrate mounting unit and a semiconductor layer is formed by using the painting unit. The painted semiconductor layer is dried with a light by using the light irradiating unit. When the light with substantially uniform wavelength is irradiated to the drain and the source electrodes, a temperature gradient is caused in the semiconductor layer. Accordingly, an organic TFT with a large carrier mobility can be manufactured.