An organic semiconductor element is provided which has the controlled crystalline state of a vapor-deposited pentacene layer and a high mobility with low voltage driving. The organic semiconductor element is formed by providing a gate electrode 101 on the surface of a substrate 102, providing thereon a gate insulating layer 103, providing on the surface of the gate insulating layer 103 an island-shaped protrusion layer 104 having dispersed and island-shaped protrusions with a low surface energy, providing on the island-shaped protrusion layer 104 a source electrode 106 and a drain electrode 107 with a distance therebetween, providing thereon an organic semiconductor layer 105 in contact with the island-shaped protrusion layer 104 and both electrodes 106 and 107, and further providing a protective film 108 on the organic semiconductor layer 105.