1. A keyword presenting device comprising: an extraction unit configured to extract a plurality of keywords from a browsing document; a determination unit configured to arrange keywords with spellings similar to each other among the plurality of keywords to obtain a plurality of groups of similar keyword; an integration unit configured to classify the keywords into main keywords that are titles and the other sub-keywords for each group of similar keywords, and to integrate the sub-keywords into the main keywords; and a presentation unit configured to present the main keywords to a user.