1. A pattern identification method for hierarchically extracting features of input data, and identifying a pattern of the input data, characterized by comprising: a first feature extraction step of extracting features of a first layer; a determination step of determining a method of extracting features of a second layer higher than the first layer on the basis of feature extraction results in the first feature extraction step; and a second feature extraction step of extracting features of the second layer on the basis of the method determined in the determination step.