1. A consensus search device comprising: a processor dividing text data of an electronic document written about at least one content object into segments of segmented text data, which refer to a predetermined minimal number of words, phrases, clauses, sentences or paragraphs, extracting at least one semantic descriptor from each of the segments of the segmented text data, and generating a semantic data index matching each of the extracted semantic descriptors to the content object and the each of the segments of the segmented text data; and retrieving a query object related to a query, based on the semantic data index, wherein the text data is divided into the segments by units of meaning, the semantic descriptor is at least one word that has a meaning, and the content object represents a topic or an entity that a user intends to describe in the electronic document, wherein the processor: generates at least one search keyword by dividing the query into words, generates extended keywords including at least one of a synonym, a hyponym and a hypernym of the search keywords, searches a semantic descriptor from each keyword and searches segmented text data included in the query object corresponding to the each semantic descriptor based on the semantic data index, detects first searched objects of which identification information is identical among all of the searched the content object included in the search for and the semantic descriptors and extracts some segmented text data of which identification information is identical among all of the segmented text data included in the first searched objects, if there are, in the query, two semantic descriptors corresponding to the keywords of which sentiments are opposite, detects second searched objects of which identification is identical among all of the searched the content object included in the search for and the two semantic descriptors and extracts all of the segmented text data in the second searched objects for the two semantic descriptors, gives a score to the each of the first and second searched objects depending on a number of the extracted segmented text data, and assigns a weight to the first and second searched objects matched to the semantic descriptor corresponding to the search keywords higher than a weight to a searched object matched to the semantic descriptor corresponding to the extended keywords, and outputs the first and second searched objects as a search result in a descending order of the score.