Sarcopenia is a syndrome characterized by progressive and generalized loss of skeletal muscle mass, strength and function. Sarcopenia has repeatedly been reported as a strong predictor of both short- and long-term outcomes following surgical treatment for breast cancer. In this study, 41 primary breast cancer cases who received surgery at our hospital were examined. To evaluate which factor amongst muscle volume, power or function would be most important to avoid sarcopenia after surgery, we examined muscle volume, power and function respectively. We also divided patients into groups by their ages or procedures of surgeries, then compared and analyzed within those groups. The results showed their grip power of the same side of their breast cancer and muscle volume of their legs has been decreased after surgeries. We also found patients who were equal or older than 75 years old and patients who received total mastectomy tended to lose their muscle volume or muscle power after their surgeries. These groups of patients would have potential risk to become sarcopenia after surgeries. It would be important to observe each of 3 factors, skeletal muscle volume, power and function to evaluate precisely their condition of sarcopenia. Tailor-made peri-operative rehabilitation programs, especially for elderly patients or patients who received total mastectomy, would be a possible solution to avoid sarcopenia after surgery for breast cancer.