1. A defect detecting device, comprising: an image acquiring device for capturing an image of an inspection object having an identical pattern sequence and acquiring the image; and a defect emphasizing device for emphasizing a defect of the captured image, wherein the defect emphasizing device includes: an inspected-point selecting device for sequentially selecting an inspection point in the captured image; and a defect emphasizing value calculator for: obtaining differences by subtracting from a luminance value of the selected inspection point each luminance value of a plurality of comparison points disposed around the inspection point in predetermined directions relative to the inspection point in order to define one difference of the smallest value of the obtained differences in luminance as a bright defect emphasizing value; and obtaining differences by subtracting the luminance value of the selected inspection point from each luminance value of the plurality of comparison points disposed around the inspection point in order to define one difference of the smallest value of the obtained differences in luminance as a dark defect emphasizing value, and wherein the defect of the captured image is emphasized by the defect emphasizing device by: selecting the inspection point and a first set of the comparison points that are located at a predetermined distance relative to the inspection point; calculating a first defect emphasizing value of the inspection point based on the first set of the comparison points; changing a distance from the inspection point to the first set of the comparison pointes in the predetermined directions to obtain a second set of the comparison points; calculating a second defect emphasizing value of the inspection point based on the second set of the comparison points; and selecting a maximum one of the defect emphasizing values among the obtained first and second defect emphasizing values as the defect emphasizing value of the inspection point that is output as a defect-emphasized result.