Primary intraosseous squamous cell carcinoma (PISCC) arising from dentigerous cysts (DCs) is rare. Herein, we present a rare case of a 35 year-old Japanese man with PISCC arising from a DC. Clinicians should be aware of the potential for malignant changes to SCC in asymptomatic DCs and should conduct follow-up. Moreover, histological examination of the entire specimen should be performed even if the lesion is suspected to be benign.