1. A defect detecting method, comprising: an image acquiring process for capturing an image of an inspection object having an identical sequence of pattern and acquiring the image; and a defect emphasizing process for emphasizing a defect of the captured image, wherein the defect emphasizing process includes: an inspected-point selecting process for sequentially selecting an inspection point on the captured image; and a defect emphasizing value calculating process 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 and selecting one difference of the smallest value of the obtained differences in luminance to determine a defect emphasizing value of the inspection point.