摘要：Basing upon the tonality analytic method, the present paper aims at： （1） Drawing attention to the subordination of the minor key vs. the major key in the chord classification, using the same methodology; and （2） Showing the differences for the major key and the minor （harmonic） key in the classification of chords, as an aspect of importance for interpreting a piece＇s tonal structure diagram. The relations between chords appearing in the major and minor （harmonic） key will be shown by applying the comparisons of： （1） third-based chords; and （2） degrees in the C major and A minor keys, on which the same diatonic chords appear.