A characteristic-data-extraction unit 13 extracts characteristic data containing changing information from song data, then an impression-data-conversion unit 14 uses a pre-learned hierarchical neural network to convert the characteristic data extracted by the characteristic-data-extraction unit 13 to impression data and stores it together with song data into a song database 15. A song search unit 18 searches the song database 15 based on impression data input from a PC-control unit 19, and outputs the search results to a search-results-output unit 21.