A 76-year-old male had a gradually expanding blackish brown nodule on his back from half a year before presentation. As the previous doctor suspected malignant melanoma, he was referred to our hospital. Histopathological examination of excisional biopsy led to a diagnosis of malignant melanoma. Preoperative radioisotope examination showed left axillary nodal drainage and faint uptake of radioactive colloid in the lateral side of left scapula. Fluorescent lymphography revealed lymphatic ow to the left scapula, and blue-stained lymph nodes were found in the lateral side of left scapula. We resected the left axillary nodes and scapula lymph nodes. The scapula lymph node was considered an interval node. Histology revealed the interval node had metastasis, but the axillary lymph node had no metastasis. After the 7th dose of nivolumab as adjuvant therapy,metastasis to lymph nodes in the left axilla was found. Left axillary lymph node dissection was performed, and 2 out of 17 lymph nodes contained metastatic disease. An interval node is a lymph node that lies along the course of a lymphatic vessel between a regional lymph node. Interval nodes contain metastatic disease at nearly the same frequency as sentinel lymph nodes in regional lymph nodes. It is necessary to recognize interval nodes, and when metastasis is suspected, identify and remove them. Skin Research, 22 : 202-207, 2023