An organic semiconductor device includes a gate electrode above a substrate. A gate insulation film is over the gate electrode. A first electrode is above the gate insulation film. A second electrode is above the gate insulation film. The second electrode is annular and surrounds the first electrode. An organic semiconductor layer is above the gate insulation film and over the first electrode. The second electrode surrounds the organic semiconductor layer and defines an outer periphery of the organic semiconductor layer. A conductive guiding member is above the gate insulation film. The conductive guiding member is annular and surrounds the second electrode. A protective film is above the gate insulation film and over the organic semiconductor layer and the second electrode. The conductive guiding member surrounds the protective film and defines an outer periphery of the protective film.