Transplantation of stem/progenitor cells is a promising, emerging treatment for heart failure (HF) in the modern era. Mesenchymal stem/stromal cells (MSCs) are considered as one of the most promising cell sources for this purpose, because of their powerful secretion of reparative factors and immunomodulatory ability. To date, various sources of MSCs have been examined for the treatment of HF in preclinical or clinical studies, including adult tissues (bone marrow and adipose tissue), perinatal tissues (umbilical cord and amnion), and pluripotent stem cells (induced pluripotent stem cells and embryonic stem cells). Adult tissue-derived MSCs have been more extensively examined. Previous clinical trials have suggested the safety and feasibility of these MSCs in HF treatment, but their therapeutic effects remain arguable. Perinatal tissue-derived MSCs have the advantages of removing the necessity of invasiveness biopsy and of mass production. An increasing number of clinical studies (albeit early stage) have been conducted. Pluripotent stem cell-derived MSCs may be another promising source because of their mass-production ability underpinned by their unlimited expansion with consistent quality. However, the risk of tumorigenicity restricts their clinical application. In this review, we summarize the current information available from preclinical and clinical studies, highlighting the advantages and disadvantages of each MSC type. This will provide an insight into consideration of the best MSC source for the treatment of HF.