There have been no studies on photodynamic diagnosis (PDD) using 5-aminolevulinic acid (5-ALA) in patients with metastatic skull tumors. Here, we present a case of skull metastasis of hepatocellular carcinoma (HCC) successfully treated by intraoperative PDD using 5-ALA. A 63-year-old man with HCC presented with a subcutaneous mass in the left occipital region. CT showed a hyperdensity mass and severe osteolytic change in the left side of the occipital bone. MRI revealed an extra-axial enhanced mass that compressed the left occipital lobe and enhancement was spreading to the adjacent subcutaneous soft tissue. In order to intraoperatively evaluate the extent of tumor invasion, PDD using 5-ALA was performed. Intraoperative PDD comfirmed that the tumor itself was highly fluorescent. Surgery was completed after comfirming the absence of residual fluorescence in the surgical field. The tumor was diagnosed HCC. Histopathological analysis confirmed that PDD accurately assessed the extent of tumor invasion. The patient was discharged home at 10 days after surgery. PDD using 5-ALA is convenient and inexpensive, and because adverse reactions are minimal, it may be useful in not only malignant glioma, but also other brain tumors.