Chord to be performed is presented to a user. Chord is detected based on one or more notes performed by the user. When it is not detected that a chord has been duly established, one of the notes performed by the user is detected as a root note of a chord. Comparison is made between the chord presented to the user and the detected chord to make a determination as to whether at least the root note of the detected chord matches the root note of the presented chord. The user is informed of a result of the determination. Thus, not only when the user has accurately executed performance operation for all component notes of the presented chord but also when the user has executed performance operation for only the root note of the presented chord, a chord performance evaluation is made, determining that the user has accurately performed.