A 78-year-old male was urgently admitted to our hospital because of consciousness disturbance. Laboratory data showed marked hypercalcemia (17.0 mg/dl), hypophosphatemia, low intact PTH level, high PTH relating peptide (PTHrP) level, normal osteocalcin and normal 1-25(OH)2D level. Computed tomography revealed a right renal tumor with extracapsular extension. Bone scintigram appeared normal. We performed right nephrectomy under the diagnosis of right renal tumor. Pathological diagnosis was poorly differentiated squamous cell carcinoma (SCC) of the right pelvis. Immunohistochemical study of the resected specimen for PTHrP was positive. Therefore, we diagnosed it as renal pelvic SCC with humoral hypercalcemia of malignancy (HHM). After nephrectomy, serum calcium returned to normal, but 5 months after nephrectomy, local recurrence appeared and serum calcium was re-elevated. She died 7 months after nephrectomy.