Background Adherence to self-care behavior is important for patients with heart failure (HF) to prevent exacerbation of HF. The aim of this study was to evaluate adherence, identify associated factors, and clarify the impact of previous HF hospitalizations on adherence in outpatients with HF. Methods A total of 116 outpatients completed a questionnaire, including the Japanese version of the European Heart Failure Self-Care Behavior Scale, to assess adherence. Results Regardless of previous hospitalizations, adherence to seek help if HF worsened was poor. Multivariate analysis adjusted for age and brain natriuretic peptide showed that diabetes mellitus and being employed were independent predictors of poorer adherence to self-care behavior ( P = .03, P = .02, respectively), but the experience of previous HF hospitalizations was not a predictor. Conclusions Self-care strategies for HF should target patients with diabetes mellitus and employed patients. Further study is necessary to develop effective programs for such patients.