The present invention provides a reticle inspection technology that enables a relative position between patterns to be evaluated for a pattern that may become a defect at the time of exposure to a sample, such as a wafer, in the double patterning technology on the same layer. An apparatus for inspecting a reticle for inspecting two reticles that are used in order to form patterns in the same layer on a substrate using the double patterning technology has: a coordinate information input unit for inputting coordinate information of a pattern of a measuring object; an image input unit for acquiring images of patterns of the two reticles based on the obtained coordinate information; an image overlay unit for overlaying the images of the two reticles at the same coordinates; a relative position calculation unit for finding the relative position between the patterns on the two reticles; an evaluation unit for assigning an index of the overlaying accuracy based on the relative position and evaluates whether the two reticles need repair; and an evaluation result output unit for outputting an evaluation result.