Background <p>Patients with breast cancer (PWBC) have a high risk of developing psychological disorders, and interventions should be implemented with care. For music therapy (MT) interventions to be more effective among these patients, providing therapeutic programs tailored to their preferences is desirable. Given the limited research on the preferences for MT of PWBC undergoing chemotherapy, we had previously conducted a qualitative study to clarify their preferences, yielding the formation of related hypotheses. Building upon these hypotheses, the current quantitative study aimed to clarify the specific preferences regarding MT of PWBC, who are undergoing chemotherapy, in Japan.</p> Methods <p>This quantitative study’s questionnaire was created based on the results of our prior qualitative study and completed by 300 PWBC undergoing perioperative chemotherapy.</p> Results <p>(a) Of all participants, 80.9% wanted MT, and there was a relationship between preferred activity type and participants’ sociodemographic and clinical characteristics; (b) the expectations of participants regarding MT differed by preferred activity type; and (c) the participants’ preferences regarding the frequency, timing, duration, and cost of the MT intervention were constant regardless of the preferred activity type.</p> Conclusions <p>As patients’ specific preferences have been clarified, we conclude that professionals may be more well-positioned and informed to devise more appropriate and effective MT programs to be incorporated into the treatment schedules of PWBC who are undergoing chemotherapy, with vital quality-of-life implications resulting.</p>