1. A method executed in a computer comprising a processor and a storage section in order to determine a weight of each feature in subjective hierarchical clustering of content expressed as a combination of physical features, the method comprising steps of: the processor acquiring multiple pieces of content separated into a triplet comprising a set of three pieces together with label information as training data, the label information indicating a pair specified by a user as having a highest degree of similarity among three pieces of the triplet, and storing the label information into the storage section; the processor executing hierarchical clustering using a feature vector of each piece of content of training data and a weight of each feature and determining a hierarchical structure of the training data; and the processor referring to the label information stored in the storage section to provide an updated weight for each feature so that a degree of agreement between a pair combined first as being in same clusters among three contents of the triplet in the hierarchical structure and a pair indicated by the corresponding label information increases.