1. A panel inspection method comprising: (a) determining if a variance value of luminance of a captured image of a panel is greater than a reference value, and searching for an original image and at least one secondary reflective image of a defect of the panel if it is determined that the variance value is greater than the reference value; and (b) determining whether the defect is an actual defect or an impurity disposed on the panel based on at least one of a difference in a luminance characteristic between the original image and the secondary reflective image and a number of the searched secondary reflective image.