An apparatus for measuring contents similarity based on feedback information from ranked users includes: a user ranking unit for receiving from a database information on users as contents creators and feedback information on contents and ranking the users based on the received information; and a user grouping unit for classifying the users into a plurality of groups based on the ranking result. The apparatus further includes: a sequence modeling unit for receiving from the database the contents and the feedback information and modeling the number of feedbacks as sequences based on the ranked user groups; and a post similarity calculation unit for measuring similarity between the modeled sequences.