A diagnosis processing apparatus for processing images of a diagnosis target existing in a structure to assess the structure , comprising: a storage unit configured to store i) data of a development-view image of the structure at a first inspection date, the development-view image being an image combining a plurality of images of the structure captured by scanning the structure , ii) position information indicating one or more positions used for capturing the plurality of images during the scanning, and iii) data of a plurality of wide-angle images captured at the first inspection date generated by capturing images of a wide area of the structure including a diagnosis target existing in the structure during the scanning, wherein the wide-angle images are associated with the position information; an acquisition unit configured to acquire data of a narrow-angle image captured at a second inspection date generated by capturing an image of an area of the structure including the diagnosis target, and data of a plurality of wide-angle images captured at the second inspection date generated by capturing images of a wide area of the structure including the diagnosis target existing in the structure ; a similar image search unit configured to search for an image similar to a specific wide-angle image captured at the second inspection date from the plurality of wide-angle images captured at the first inspection date; and a display control unit configured to display a partial area image of the development-view image captured at a scanning position indicated by position information associated with data of a specific wide-angle image captured at the first inspection date as a narrow-angle image captured at the first inspection date, wherein the specific wide-angle image captured at the first inspection date is determined to be similar to the specific wide-angle image captured at the second inspection date and used for the searching. a storage unit configured to store i) data of a development-view image of the structure at a first inspection date, the development-view image being an image combining a plurality of images of the structure captured by scanning the structure , ii) position information indicating one or more positions used for capturing the plurality of images during the scanning, and iii) data of a plurality of wide-angle images captured at the first inspection date generated by capturing images of a wide area of the structure including a diagnosis target existing in the structure during the scanning, wherein the wide-angle images are associated with the position information; an acquisition unit configured to acquire data of a narrow-angle image captured at a second inspection date generated by capturing an image of an area of the structure including the diagnosis target, and data of a plurality of wide-angle images captured at the second inspection date generated by capturing images of a wide area of the structure including the diagnosis target existing in the structure ; a similar image search unit configured to search for an image similar to a specific wide-angle image captured at the second inspection date from the plurality of wide-angle images captured at the first inspection date; and a display control unit configured to display a partial area image of the development-view image captured at a scanning position indicated by position information associated with data of a specific wide-angle image captured at the first inspection date as a narrow-angle image captured at the first inspection date, wherein the specific wide-angle image captured at the first inspection date is determined to be similar to the specific wide-angle image captured at the second inspection date and used for the searching. <EOS>