Abstract: A dark spot defect of an EL element is detected based on an emission brightness or a current flowing through the EL element when an element driving transistor which controls a drive current to be supplied to the EL element is operated in its linear operating region and the EL element is set to an emission level. A dim spot defect caused can be detected based on a current flowing through the EL element when the element driving transistor is operated in its saturation operating region and the EL element is set to the emission level. When an abnormal display pixel is detected based on an emission brightness, a pixel which is determined as an abnormal display pixel and which is not determined as a dark spot defect is determined, and the pixel is detected as a dim spot defect caused by the characteristic variation of the element driving transistor.