Chest wall metastases from malignant tumors are rare and the majority of them are from adjacent structures such as the breast, lung, pleura, and mediastinum. Paticularly, chest wall metastases from distant organs are an even rarer event. There are few reports of chest wall metastasis with obscure or absent primary tumor. A 51-year-old man was diagnosed with metastatic hepatocellular carcinoma after an operation for a palpable mass on his left upper chest wall, At that time, there was no evidence of primary hepatocellular carcinoma in the liver after various examinations. We report a case of chest wall metastasis from unknown primary hepatocellular carcinoma.