We herein report the case of a patient with a juxtaglomerular cell tumor (JCT). Dynamic enhanced computed tomography revealed a small nodule on the surface of the lower pole of the right kidney. Selective renal venous sampling showed an elevated level of plasma renin activity (PRA) in the right lower pole renal vein only. We performed right partial nephrectomy and diagnosed the patient with JCT. Making a diagnosis of JCT is often difficult due to the small size of the tumor and the lack of lateralization of the PRA on renal venous sampling. This case highlights the importance of performing selective renal venous sampling for the preoperative diagnosis of JCT.