In one embodiment, a mask pattern verification apparatus is disclosed. The mask pattern verification apparatus can include a library registration portion registered a clean circuit pattern, a memory portion saved a design circuit pattern, a verification circuit pattern, a verification mask pattern, and a verification wafer pattern, a mask verification portion performing mask verification to the verification mask pattern, a lithography verification portion performing lithography verification to the verification wafer pattern, and a CPU including a library registration circuit registering the clean circuit pattern to the library registration portion, a pattern matching circuit verifying the clean circuit pattern being set or not in the design circuit pattern, a verification pattern extraction circuit extracting the verification circuit pattern from the design circuit pattern, an OPC circuit performing OPC to the verification circuit pattern, a mask verification circuit controlling the mask verification portion, and a lithography verification circuit controlling the lithography verification portion.