A pattern defect detecting method and apparatus are disclosed on a connectivity processor to input a binary picture signal pattern and a pad position coordinate and outputting connectivity data between pads. Here, the connectivity processing refers to a processing for giving the identical number to one aggregation of connected or linked pads for the pads given to a serial pattern. In the connectivity processor wherein a plane on which the drawn pattern to be inspected is scanned by a linear sensor, the connectivity processing can be releazed almost concurrently with the scanning by driving a temporary memory.Also, a pattern defect detecting apparatus the above-mentioned connectivity. The invention processing coping with the difficulties of a required inspection level, and also represents a processing time of each embodiment theoretically. A moving time of the bed on which an inspecting object is placed and others are added to the real processing time.