A substrate having organic thin film capable of growing two dimensionally such organic thin film as C60 and a transistor using the same are constituted with a substrate (1) having organic thin film by sequentially depositing a buffer layer (3) and organic thin film (4) on the substrate (2), and with the buffer layer orienting the organic thin film (4). A layer easily oriented with the substrate (2) and the buffer layer (3) may be inserted between the substrate (2) and the buffer layer (3). A sapphire substrate as the substrate (2), pentacene or pentacene fluoride as the buffer layer (3), and C60 or rubrene as the organic thin film (4) may be used, thereby C60 or rubrene two dimensional thin film of high quality can be obtained. By using such a substrate (1) having organic thin film, a field effect transistor of high quality can be realized.