An organic light emitting diode display includes a thin film transistor on a substrate (1). The thin film transistor includes a gate electrode (2), a gate insulating film (3) that covers the gate electrode (2), a first semiconductor film (4) provided on the gate insulating film (3), a second semiconductor film (5) provided on the first semiconductor film (4), a back channel protection insulating film (7) and an ohmic contact film (8) provided on the second semiconductor film (5), and source/drain electrodes (9). A crystallinity of the first semiconductor film (4) is higher than that of the second semiconductor film (5). The back channel protection insulating film (7) is formed as one of an organic insulating film and an organic/inorganic hybrid insulating film. The thin film transistor has excellent off-state characteristics, swing characteristics, and saturation characteristics.