1. A pattern inspecting apparatus for inspecting patterns in numerous chips formed on a substrate, comprising: a substrate support for supporting said substrate; a camera for acquiring images of said chips; moving means for moving said substrate support and said camera relative to each other; an image memory for storing the images of said chips acquired by said camera; an area setting mechanism for setting a repetitive pattern area having repetitive patterns formed therein, and a random pattern area having random patterns formed therein, to each of said chips whose images are acquired by said camera; an area memory for storing said repetitive pattern area and said random pattern area; a cell comparing inspection unit for executing a cell comparison to detect a pattern defect by comparing the repetitive patterns in said repetitive pattern area set to each of said chips and stored in said area memory; and a chip comparing inspection unit for executing a chip comparison to detect a pattern defect by comparing corresponding patterns in said repetitive pattern area and said random pattern area set to said chips and stored in said area memory.