A stage apparatus (100) includes a stage glass (210) having on an upper surface a stage surface (211) of a substantially flat plane on which a predetermined workpiece (W) is set, a plane light emitter (220) with a flat plane, which is provided to substantially all over a lower surface of the stage glass (210) and illuminates the workpiece (W) with contour illumination through the stage glass (210), and a supporting section (300), which supports at plurality of points on a lower face side of the plane light emitter (220) and adjusts the flatness of the stage surface (211) by adjusting the height at a plurality of supporting points.