14. The information extraction method according to claim 13 , wherein the pattern determining step determines a forward character string and a backward character string of the phrase included in the input word list as patterns, the phrase candidate extracting step extracts a character string interposed between the forward character string and the backward character string from the document and determines the extracted character string as a candidate of a phrase, and the phrase selecting step selects a phrase of an output subject from the candidates of the phrases, which are extracted by the phrase candidate extracting step.
14. The information extraction method according to claim 13 , wherein the pattern determining step determines a forward character string and a backward character string of the phrase included in the input word list as patterns, the phrase candidate extracting step extracts a character string interposed between the forward character string and the backward character string from the document and determines the extracted character string as a candidate of a phrase, and the phrase selecting step selects a phrase of an output subject from the candidates of the phrases, which are extracted by the phrase candidate extracting step. 15. The information extraction method according to claim 14 , wherein the phrase selecting step calculates a phrase score indicating a value of a degree of importance of a candidate of the pattern used in specifying the candidate of the phrase or the amount of documents where the candidate of the phrase appears for each of the candidates of the phrases, and selects the candidate of the phrase having a phrase score is equal to or larger than a predetermined threshold value as the phrase of the output subject.