Musical key determining device

Melody and chord information of a music piece are supplied. On the basis of the chord information, one or more possible musical keys are nominated. Then, on the basis of the melody information, it is judged in a collating manner whether it is proper to determine any of the possible musical keys as a musical key of the music piece. For instance, the possible musical keys are nominated on the basis of detection of a dominant motion, since the dominant motion in a chord progression strongly suggests specific musical keys. For instance, of the nominated possible musical keys, those which do not contain all of the melody notes as their scale note are excluded, and a single musical key which contains all of the melody notes as its scale note is determined as the musical key of the music piece. With such arrangements, it is allowed to make a musical key determination which is very reasonable from a musical point of view.