A keyword related to a user's interest is acquired. A keyword acquiring device including a tree storage unit that stores a keyword tree obtained by performing hierarchization according to the number of appearances and relevance in advance using a keyword associated with content as a node records a keyword associated with content previously selected by a user as a log, extracts a plurality of keywords based on a predetermined condition from a log corresponding to a certain user recorded in the log, extracts a partial tree including the extracted keywords from the keyword tree, and acquires a keyword in a node having no other lower node as a keyword related to the user's interest.