An assistive music playing apparatus plays a music piece with musically acceptable notes even when the player inputs musically unacceptable notes. The apparatus provides a chord progression pattern, and comprises a note conversion device. A chord progression pattern defines a series of chords, which are presented one after another in time for a music progression. As the player plays music, inputting potentially unacceptable notes, the inputted notes will be converted to musically acceptable notes with reference to the currently presented chord in the chord progression. The note conversion rules are prepared different for a melody note range, a chord note range and a bass note range. Overlap of converted notes are avoided. Depending on the conditions of the player's note input, i.e., whether the melody is ascending or descending, or the chord is played in a block chord or in an arpeggio, the conversion rules may be selected to generate notes which fit the designated chord, even including non-basic notes or tension notes.