A contents retrieval device (100) presenting an appropriate related keyword to a user even when an object user wishes to retrieve dynamically changes. The contents retrieval device (100) includes a contents estimation unit (107) retrieving contents according to a search keyword, a document space database (103) storing document spaces according to an occurrence frequency of the keyword, a document space selection unit (104) selecting a the narrowing-down document space and an expansion document space from the document space database (103) according to the search keyword and the occurrence frequency of the document space indicating a degree of relevance with the contents according to the search keyword, a related keyword estimation unit (108) selecting keywords corresponding to the narrowing-down document space and the expansion document space as a narrowing-down keyword and an expansion keyword, respectively, and an output unit displaying the selected narrowing-down and expansion keywords.