Abstract: The present invention makes it possible for unskilled to inspect the total surface of a liquid crystal panel accurately in short time. It is defined that a liquid crystal panel can be divided into a single part which is a constituent, isolable, and an inspectable area, and that the single part to be "unit area of image" which is defined as a pattern to be inspected. Before the inspection, a unit area of an image without defect is selected from a liquid crystal panel to be inspected. The upper limit reference pattern and the lower limit reference pattern are generated by giving the maximal brightness in a convolution and adding the predetermined brightness and by giving the minimal brightness in the convolution and subtracting the predetermined brightness, respectively, to each pixel of the convolution.