1. A hardness tester for measuring hardness of a sample by applying a predetermined test force to a surface of the sample with an indenter to form an indentation and measuring dimensions of the indentation, the hardness tester comprising: an indentation former configured to form the indentation in the surface of the sample by pressing the indenter against the surface of the sample; an image capture controller configured to control an image capturer to capture an image of the surface of the sample and obtain image data of the surface of the sample; an indentation area extractor configured to extract an indentation area formed in the surface of the sample based on the image data of the surface of the sample obtained by the image capture controller, the indentation area extractor comprising: a reduced image generator configured to reduce the image obtained from the image data of the surface of the sample at a scale ratio selected from a plurality of predetermined scale ratios, the reduced image generator further configured to generate a reduced image; and a pattern matcher configured to perform pattern matching with respect to the reduced image generated by the reduced image generator, the pattern matcher further configured to extract the indentation area; and a hardness calculator configured to calculate the hardness of the sample based on the indentation area extracted by the indentation area extractor.