An information retrieval apparatus, which can present to a user only a related word matching a user search intent, includes: an associative dictionary storage unit for storing words included in plural pieces of text to be searched and relevance degrees between the words; an appearance frequency storage unit for storing an appearance frequency that is the number of pieces of text in which the words stored in the associative dictionary storage unit appear, among the plural pieces of text to be searched; and a related word obtaining unit that obtains a related word to be presented to the user, from the relevance degree between the search word entered by the user and another word among the words, the appearance frequency, and the user search intent.