A method for providing a mutual-liking-based chat service is disclosed. A method by which a server provides a chat service, according to an embodiment of the present invention, may comprise the steps of: receiving mutual liking scores between users from user terminals; calculating a summed score for each of other users by summing a liking score which a first user has assigned to each of the other users and a liking score assigned from each of the other users, if a special chat room opening request of the first user among the users is received; selecting a second user corresponding to the highest score from among the summed scores; and opening a special chat room between the first user and the second user.