The quality of life (QOL) of 21 patients with advanced or recurrent breast cancer was assessed using a QOL measure developed by the Ministry of Welfare in Japan: The QOL Questionnaire for Cancer Patients Treated with Anticancer Drugs (QOL-ACD). The factors that improve the QOL were analyzed by multiple regression analysis. The difference of the QOL score between pre- and post-treatment was set as a dependent variable, and sociodemographic and therapeutic characteristics were set as independent variables. The results revealed that the improvement of the QOL score had close associations with therapeutic efficacy (TE) and shorter disease-free interval (DFI). In the analysis using the mean scores of the four categories of the QOL (activity, physical, psychological and social aspects) as dependent variables, activity had a close association with shorter DFI; physical aspect had close associations with TE and shorter DFI; and the psychological aspect had close associations with chemoendocrine therapy and less lines of previous therapies. The results suggest that, to improve the QOL of patients with advanced or recurrent breast cancer, we should attempt to obtain higher efficacy of treatments such as endocrine therapy for patients with shorter DFI in the earlier period of their clinical course.