1. A method of building information on an emotion lexeme comprising: retrieving documents on the web on a basis of an original emotion expression lexeme from a sentence which is input, and deriving emotion basis lexemes of the original emotion expression lexeme from sentences of the retrieved documents including the original emotion expression lexeme; deriving a new emotion basis lexeme, the new emotion basis lexeme being determined among the emotion basis lexemes according to at least one predefined new lexeme criterion, and then storing the new emotion basis lexeme in a database; retrieving documents on the web on a basis of the new emotion basis lexeme and then deriving emotion expression lexemes related to the emotion basis lexemes from sentences of the retrieved documents including the new emotion basis lexemes; deriving a new emotion expression lexeme, the new emotion expression lexeme being determined among the emotion expression lexemes according to at least one predefined new lexeme criterion, and storing the new emotion expression lexeme in the database; and assigning an emotion strength to the new emotion expression lexeme and then storing the emotion strength of the new emotion expression lexeme in the database, wherein the emotion strength is calculated by multiplying an emotion strength value of the new emotion expression lexeme by a sum of weights of a plurality of modifiers.