1. A song search system that searches for desired song data from among a plurality of song data stored in a song database, the song search system comprising: a song-data-input means of inputting said song data; a characteristic-data-extraction means of extracting physical characteristic data from song data input by said song-data-input means; an impression-data-conversion means of converting characteristic data extracted by said characteristic-data-extraction means to impression data determined by human emotion; a memory-control means of storing impression data converted by said impression-data-conversion means in a song database together with song data input by said song-data-input means; an impression-data-input means of inputting impression data as search conditions; a song search means of searching said song database based on impression data input from said impression-data-input means; and a song-data-output means of outputting song data found by said song search means.