It is possible to blast air on a surface portion of a measured object from a hole of pressing means, project illumination light in a concentric pattern with an optical element and shoot the measured object with a CCD so as to visually grasp hardness distribution on the surface portion from distortion of the concentric pattern displayed on an observed image. As for the hardness distribution, it is possible to detect luminance distribution of a measured object image obtained by the CCD so as to display the concentric pattern which is the luminance distribution as a conspicuous representation of the hardness distribution. And the luminance distribution can also be represented in the concentric pattern by multiplying a luminance value by an overflowing coefficient.