2. The text analysis device according to claim 1 , further comprising: user opinion specifying means configured to specify an opinion of a specified user, out of the users who participate in the discussion; and display means configured to display a change in opinion of the specified user based on the detected change point and to display an opinion having influence on the opinion of the specified user or an opinion influenced by the opinion of the specified user.
2. The text analysis device according to claim 1 , further comprising: user opinion specifying means configured to specify an opinion of a specified user, out of the users who participate in the discussion; and display means configured to display a change in opinion of the specified user based on the detected change point and to display an opinion having influence on the opinion of the specified user or an opinion influenced by the opinion of the specified user. 4. The text analysis device according to claim 2 , wherein, with respect to the user who participate in the discussion, the number of times the user's opinion changes is counted, the number of opinions influenced by the opinion of the user is counted, and the character of the user is specified based on the number of times changed and the number of opinions counted.