1. A feature amount generation device comprising: a feature point detecting unit configured to detect a feature point from an input image; a pixel information generating unit configured to generate pixel information from pixel values of surroundings of the feature point in the input image; a feature point pixel information distribution generating unit configured to generate a first distribution of pixel information of a first region including the feature point; a sub-feature point detecting unit configured to detect sub-feature points which are feature points in the surroundings of the feature point; a sub-feature point pixel information distribution generating unit configured to generate second distributions of pixel information of second regions including the sub-feature points; and a feature amount generating unit configured to generic a feature amount at the feature point based on the first distribution and the second distributions.