1. A picture matching processing system, comprising: a window picture cutting part for cutting out characteristic window pictures from a previously captured recognition target picture; a capturing environment variation influence evaluating part for evaluating the influence of variations in a capturing environment of the cut out window pictures; and a window picture selecting part for selecting a window picture in which the influence of variations in a capturing environment is at a predetermined level or less among the cut out window pictures, based on results of the evaluation of the influence of variations in a capturing environment, wherein picture matching is conducted by using the selected window picture.