Malignant melanoma(MM) is a neoplasm of melanocytes and typically occurs in the skin. Also, more than 97% of melanomas are developed with a known primary site. Rarely, melanoma appeared without obvious primary site, and is called melanoma of unknown primary(MUP). MUP defined by the presence of melanoma in distant subcutaneous sites, lymph nodes, or visceral organs without an obvious cutaneous, ocular, or mucosal primary site. A 70-year-old man visited our clinic complaining of firm, round shaped skin-colored subcutaneous mass on posterior neck 5 months ago. One month later, a solitary, firm, dome-shaped erythematous indurated nodule appeared suddenly on left parietal scalp. Skin biopsy from the lesion showed the tumor nodules were observed in the dermis and tumor cells were positive for HMB45, S-100 and Melan A. Based on the histopathologic findings, we diagnosed with MM. So we took excisional biopsy on the posterior neck which suspected original site and it diagnosed MM also. He transferred the department of hematology-oncology for systemic evaluation to find primary site and progression to other site also. Typically, melanomas are discovered during routine skin examination using the “ABCDE” rule. However, in our case, it was difficult to diagnose at first because of clinical presenting as subcutaneous mass. So we herein report a case of malignant melanoma of unknown primary presenting as subcutaneous mass on the scalp.