1. An age estimation apparatus for estimating an age of a person on image data, comprising: a dimension compression unit for applying dimension compression to the image data to output low dimensional data; and an identification unit for estimating an age of a person on the basis of a learning result using a feature amount contained in the low dimensional data, wherein a parameter used for the dimension compression by the dimension compression unit and the feature amount used for age estimation by the identification unit are set on the basis of a result of an evaluation of a generalization capability using a weighting function that shows a degree of seriousness of an estimated age error for every age.