We herein report a case of hypovascular renal tumor in which microvascular blood flow diagnosis by Sonazoid®-enhanced ultrasonography was possible. Abdominal ultrasonography (US) and magnetic resonance imaging (MRI) performed at another institution detected a left renal mass in a 75-year-old man with renal dysfunction. At our hospital, non-contrast computed tomography (CT) detected a mass at the same site. Staining was seen from the tumor margin to the interior of the tumor on contrast-enhanced ultrasonography using Sonazoid®. Therefore, malignancy was suspected, and translumbar partial nephrectomy was performed. The tumor was diagnosed as a papillary renal cell carcinoma based on histopathologic examination. In cases such as this in which contrast-enhanced CT is contraindicated, Sonazoid®-enhanced ultrasonography is useful for microvascular blood flow diagnosis of renal masses.