1. A method for reinspecting a prescription drug, the method comprising: receiving a result information of primary inspection for a defect of a drug pack from a prescription server and a primary drug pack inspection module through a drug pack information transceiving module; acquiring and analyzing an image of a defective drug pack through an image processing module; and determining a defect state of the drug pack by comparing an inspection result of the primary drug pack inspection module with the image of the defective drug pack through a defect analyzing module, wherein the acquiring and analyzing of the image of the defective drug pack comprises: photographing the prescription drug in a form of an RGB image and collecting the RGB image; extracting a B channel from a collected drug image; acquiring a black & white image of the prescription drug; inputting the black & white image of the prescription drug; creating a binary image by using a critical value; separating linked drug regions from each other in the binary image; extracting an independent region of each drug; extracting a size, a central point, and an amount of the independent region; and determining if a size and an amount of the photographed prescription drug matches with a size and an amount of a drug according to a prescription information.