We herein present the case of a patient with myeloma and chronic kidney disease (CKD) who developed rapidly progressive vascular and soft tissue calcification during the course of treatment for severe hypocalcemia induced by the administration of denosumab for myeloma and hypercalcemia. Because a large amount of supplementation with active vitamin D and calcium was required to correct the severe hypocalcemia, rapidly progressive vascular calcification developed. Seeing that patients with CKD are prone to developing severe and prolonged hypocalcemia after denosumab treatment, physicians should closely monitor the patients' serum calcium levels and manage their hypocalcemia appropriately so as to avoid the development of significant ectopic calcification.