Sorafenib is a newly approved multikinase inhibitor for the treatment of unresectable hepatocellular carcinoma (HCC) and advanced renal cell carcinoma. Sorafenib is associated with a relatively high incidence of cutaneous adverse events. We report the first case of 88-year-old man with HCC who developed keratoacanthoma (KA) during sorafenib therapy in Japan. He presented with a hyperkeratotic papule on right forearm 6 months after starting sorafenib. Excisional biopsy confirmed the clinical diagnosis of KA. Recently, in the English literatures, KA and squamous cell carcinoma (SCC) have been reported to occur in 6-7% of the patients treated with sorafenib, but, in Japan, the development of KA or SCC has not been described in association with sorafenib. Careful dermatologic monitoring of these patients to ensure early detection of KA or SCC is recommended.