A method of automatically generating accompaniment chords in an electronic musical instrument system, whereby, as a melody is advanced, corresponding accompaniment chords can automatically be generated. The method comprises the steps of inputting the key of the tune to be played, drawing up fundamental chords to be used in the play tune according to the input tune key, inputting melody notes,
... [Show full abstract] comparing the input melody notes with the notes constituting the fundamental chords to select the highest priority one among the fundamental chords, and outputting the selected highest priority chord, together with the melody notes.