A 56-year-old man suffered from cutaneous squamous cell carcinoma (cutaneous SCC) which occurred on a cutaneous lesion of sporadic porphyria cutanea tarda (sporadic PCT). His liver function decreased from the time he was infected with Schistosoma japonicum at the age of 10. He drank a little alcohol. Erythematous maculae with blisters or erosions occurred on sun-exposed areas of his skin when he was 52. His urine continued to be red. After detailed examinations including liver biopsy, he was diagnosed as having sporadic PCT due to liver disorder after infection with Schistosoma japonicum. At the age of 56, a small red papule arose on his right earlobe at the site of a sporadic PCT lesion. The papule rapidly enlarged with ulceration; this completely destroyed his right earlobe, which was covered with odoriferous yellow-white necrotic tissue. The tumor then extended to his right preauricular area with ulceration. A skin biopsy confirmed well-differentiated cutaneous SCC. The association of cutaneous SCC with sporadic PCT has not been previously reported; we think that the association is significant. Such an occurrence may have been induced by either direct or indirect effects of ultraviolet light or a scar formed by the sporadic PCT.