1. An apparatus for inspecting a reticle that inspects two reticles used in order to form patterns on the same layer on a substrate using the double patterning technology, comprising: 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 a relative position between the patterns on the two reticles; an evaluation unit for assigning an index of 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.