1. A portable communication device for extracting a user interest, the device comprising: a term vector generation unit for generating, based on types of text data stored in the portable communication device, a term vector representing each text data; a subject classification tree storage unit for storing a subject classification tree, which is a tree structure in which multiple nodes, each including at least one training data and representing a subject, are connected to one another; and a similarity calculation unit for calculating a similarity between the term vector and the training data for each node in the subject classification tree, wherein the similarity calculation unit extracts a node name representing the user interest from the subject classification tree based on the similarity.