A document search device includes a document search unit configured to search for an input keyword in a document database in which document information including text data is stored, the text data being extracted, by using a character recognition process, from document image data generated by imaging a paper document, a similar keyword selecting unit configured to select a similar keyword in accordance with a degree of similarity to the input keyword, from a group of wildcard strings generated from the input keyword, and cause the document search unit to search for the similar keyword in the document database, and an output unit configured to output a search result obtained by searching for the input keyword in the document database and a search result obtained by searching for the similar keyword in the document database.