A control unit shifts an imaging unit relatively with respect to a stage to take an image of a measuring object at a plurality of places by the imaging unit and thereby obtain a plurality of images, and generates a composite image of the measuring object having a range which is wider than an imaging range of the imaging unit by combining the plurality of images. The control unit shifts the imaging unit relatively with respect to the stage such that parts of images adjacent to one another obtained by the imaging unit overlap, and performs an image matching processing that performs image matching of an overlapped portion of the adjacent images. The control unit generates the composite image of the measuring object by joining the adjacent images at a position where the image matching is performed in the image matching processing.