A case of ungual malignant melanoma was described. A 66 year-old female visited to our hospital because of a 2cm sized blackish nodule with nail destruction on her left thumb.Amputation of the left thumb at the distral end of metacarpal bone and left axillar lymphnode dissection was performed under a clinical diagnosis of ungual malignant melanoma. On histological examination, the tumor was composed of pigmented anaplastic melanocytes, which invaded the bone underneath. Immunohistochemically, the cells were positive for S-100 protein and HMB-45. No metastatic lesion was detected on her left axilla. She received 4 courses of combination chemotherapy, DAY (DTIC, ACNU, VCR) along with local IFN-β injection. Six months later, she noticed a swelling on her left axilla and we re-performed lymphnode dissecton followed by a combination chemotherapy CDV (CDDP, DTIC, VDS).She is now in good condition without evidence for metastasis for the last 13 months.