A music signal processing apparatus, a method, and a program are provided. The music signal processing apparatus includes a frequency spectrum transform unit, a filter, a frequency feature amount generation unit, and a melody feature amount sequence acquisition unit. The frequency spectrum transform unit is configured to transform a music signal into a frequency spectrum, wherein the music signal is a signal of a musical piece containing a part with a melody. The filter is configured to remove a steep peak of the frequency spectrum. The frequency feature amount generation unit is configured to generate, from a signal output from the filter, a frequency feature amount in which a fundamental frequency component of the part is emphasized. The melody feature amount sequence acquisition unit is configured to acquire, based on the frequency feature amount, a melody feature amount sequence that specifies a fundamental frequency of the part at each time.