1. A method for recommending other users who have similar preference with one or more specific users comprising the steps of: (a) acquiring information on objects selected, respectively, by one or more specific users and random other users, wherein the random other users include 1-st to r-th other users while the objects include 1-st to s-th objects and a specific object is selected among the 1-st to s-th objects by the specific users; (b) acquiring information on topics which include 1-st to n-th topics by dividing the objects into n groups by referring to one or more characteristics of each object; (c) determining to which topic the one or more specific users and the random other users respectively correspond; (d) determining a probability of the one or more specific users (U 1 ) and the k-th other user (U 2 ), at the same time, having selected the specific object (O), P(O, U 1 , U 2 ), by referring to correspondence relationships between user information which includes: information on the one or more specific users and the k-th other user, topic information, and information relating objects to topics, wherein k is between one and r, by evaluating a degree of user similarity between the one or more specific users compared to each other user, comprising: (d1) determining P(O|T), the probability of the specific object appearing in the state of a random topic, and P(T|U), the probability of the random topic appearing in the state of both the one or more specific users and the k-th other users; (d2) multiplying the P(O|T) by the P(T|U) for each of the 1-st to n-th topics; (d3) summing the multiplied respective values for the 1-st to n-th topics; (d4) evaluating the degree of user similarity by multiplying the summed value by P(O), the probability of the specific object appearing independently; and (e) recommending one or more specific other users among the random other users who are ranked in top levels in terms of the degree of user similarity as appropriate users who have similar preference with the one or more specific users.