An accompaniment data generating apparatus has a storing portion 15 for storing sets of phrase waveform data each related to a chord identified on the basis of a combination of chord type and chord root, and a CPU 9. The CPU 9 carries out a chord information obtaining process for obtaining chord information by which a chord type and a chord root are identified, and a chord note waveform data generating process for generating phrase waveform data indicative of chord notes of the chord root and the chord type identified by the obtained chord information in accordance with the obtained chord information by use of the sets of phrase waveform data stored in the storing portion 15, and outputting the generated data as accompaniment data.