The conventional light-emitting element formed by an electroluminescent material has a problem due to poor color purity of light emission. Accordingly, it is an object of the present invention to provide a high luminance and high efficiency light-emitting device formed by an organic compound material. The invention provides a light-emitting device in which an organic compound layer that emits light having an emission peak with a half-band width of at most 10 nm upon applying current is interposed between a pair of electrodes is provided. The variation of emission peak intensity depending on a current density can be sorted by two linear regions with different gradients. A region of a sharp gradient is at a higher current density side compared to a region of a slow gradient. TFTs are provided to each pixel in order to perform active matrix driving.