In an interactive program search apparatus (100) which presents search condition candidates for expanding or narrowing down search results, reason words indicating the reason why the search condition candidates are presented are adaptively determined based on user's preference, search actions, and watching actions. An association-source word extracting unit (109) extracts an association-source word from the program search results, and an associated word extracting unit (110) extracts associated words associated with the association-source word, from an association dictionary storage unit (103). A reason word extracting unit (111) extracts reason words illustrating the relationships between the association-source word and the associated words, using the association-source word, the associated words, and the obtainment history information composed of words included in the program information of the programs selected by the user in the past and selected words among the words.