1. A pattern verification-test method of verifying or testing a mask pattern, the method comprising: deriving an illumination condition at a verification-test subject position in a photomask surface of a mask pattern as a verification or a test subject based on the verification-test subject position and illumination condition information about a distribution of an illumination condition in a photomask surface of exposure light with which an exposure apparatus irradiates the mask pattern; performing lithography simulation on the mask pattern based on the illumination condition at the verification-test subject position and the mask pattern; and verifying or testing the mask pattern based on a result of the lithography simulation.