Nivolumab, which has a promising anti-tumor efficacy and a manageable safety profile, has being rapidly introduced in metastatic renal cell cancer therapy in Japan. We evaluated the efficacy and adverse events of nivolumab in real world clinical practice in Japan. The medical records of 45 consecutive patients who started treatment with nivolumab, up to September 2018, were reviewed and statistically analyzed. The median follow-up period was 22.3months. The best responses were a complete response in three patients (8%), a partial response in 14 patients (36%), stable disease in 14 patients (36%), and progressive disease in eight patients (20%). The median progression-free survival period and 1 year progression-free survival rate were 14.9months and 54.5%, respectively. The estimated overall survival period and 1-year and 2-year overall survival rates from initiation of nivolumab were not reached, and 91.1%, and 86.2%, respectively. Twenty-seven patients (60%) experienced adverse events including four (10%) severe adverse events (Grade 3 or 4). The most common adverse event was rash (n = 9, 20%). Five patients discontinued nivolumab therapy, because of an adverse event (Grade 3 diarrhea, one patient; Grade 2 fatigue, one patient; Grade 3 uveitis, two patients; and Grade 3 adrenal insufficiency, one patient). Nivolumab has a relatively favorable efficacy and safety profile for Japanese metastatic renal cell cancer patients in clinical practice.