The blue nevus consists of papules or a plaque-like aggregate of aberrant dermal melanocytes actively producing melanin in the reticular dermis. The common blue nevus clinically presents as a 2~10 mm sized, well-demarcated, papular, bluish-black lesion, typically on the dorsal surface of the hands or feet. However, it has rarely been reported on the mucosal lesions such as the oral cavity. It is usually seen as an aquired form. We report a case of a large, congenital, common blue nevus on the upper lip.