In order to assess, with high accuracy, a degree of a change having occurred in a structure, the present invention includes: a Betti number calculating section (42) configured to (I) generate, with respect to a single captured image obtained by capturing an image of a structure, a plurality of binarized images having respective binarization reference values different from each other and (II) calculate, for each of the plurality of binarized images, a first characteristic numerical value indicative of the number of connected regions each of which is obtained by connecting pixels each having one of pixel values obtained by binarization; and a prediction score determining section (44) configured to determine, in accordance with a result of a comparison, information on a change having occurred in the structure, the comparison having been made between (i) a pattern indicative of a relationship between (a) the respective binarization reference values and (b) the first characteristic numerical value and (ii) a predetermined reference pattern.