1. A method of constructing a user profile using a content tag, the method comprising: directly extracting a content tag from tag information added to a digital content; receiving an input for a tag specified by the user of the digital content when the tag cannot be directly extracted from the digital content; generating a user profile of the user of the digital content using the extracted tag or the tag input by the user of the digital content; and storing the profile of the user of the digital content, wherein a preference value for the extracted tag or the tag input by the user of the digital content is generated by adding up the preference values of digital contents including the tag.
3. The method of claim 1 , wherein the generating of the user profile using the extracted tag or the tag input by the user of the digital content comprises combining the preference value for the digital content used by the user of the digital content with an existing preference value for the tag for the user of the digital content.