NOVELTY - The apparatus has an image transfer unit (55) for transferring image data obtained by imaging a region on substrate and stored in a buffer memory (53) to image processing memories. The image processing units (59) perform inspection process for defect detection on image data corresponding to the region to be processed out of the transferred image data. Multiple image processing control units (4) are provided for acquiring inspection tasks with inspection details and for controlling multiple image processing units independent of image transfer by the image transfer unit.    USE - Appearance inspection apparatus for detecting defect of pattern on substrate e.g. semiconductor substrate. Can also be used in detecting defect of pattern on glass substrate for photo mask, substrate for display device, substrate for optical disk, substrate for magnetic disk, substrate for magneto-optic disk, printed circuit board, and substrate for solar battery.    ADVANTAGE - Since the transfer of the image data obtained by imaging operation of the imaging unit and the inspection process performed by the image processing unit are performed independently of each other, the image data can be transferred from the image storing memory to the image processing memory with high transfer efficiency. Therefore, the decrease in the transfer efficiency due to the overhead in the image transfer is avoided and an efficient inspection is achieved. The control on load ratio for processor elements is advanced in a good balance so that the delay time of inspection is decreased. The decrease in the transfer efficiency due to the overhead in the image transfer is suppressed, since the image data is transferred in relatively large data amount in one operation and an efficient and reliable inspection is ensured. The higher-speed computations are possible for the image processing relating to defect detection.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an appearance inspection method for detecting a defect of a pattern of a substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a functional block diagram of the appearance inspection apparatus.    Control unit (4)    Inspection unit (5)    Buffer memory (53)    Image transfer unit (55)    Image processing unit (59)