Sudden appearance of black spots on the face may be caused by sun spots, melanoma or pigmented nevus and other diseases. 1. Sun spots: long time sun exposure or ultraviolet irradiation, such as playing at the beach without paying attention to sunscreen, may appear on the face of the phenomenon of the sudden appearance of black spots, for the formation of sun spots after intense sun exposure. 2. Melanoma: it is a kind of malignant skin tumor, which is a malignant transformation of melanocytes, and can be manifested as nevus-like, malignant freckle-like, nodular type and so on. If black spots suddenly appear on the face, and rapidly rise and increase in size, one should be alert to melanoma. 3. Nevus pigmentosus: nevus pigmentosus is caused by benign proliferation of certain misshapen tumors or melanocytes, resulting in the sudden appearance of black spots on the face. The etiology is unknown, and it is related to congenital heredity and developmental defects. Facial black spots may also be related to other diseases, it is recommended to go to the regular hospital in time, under the guidance of specialized doctors for regular treatment.