A very small black bump on the foreskin can be considered a congenital nevus, excessive friction or inflammatory stimulation and HPV (human papillomavirus) infection, etc. It is recommended to go to the hospital for further examination to clarify the cause. 1. If the nevus is congenital and there is no change in its size in the past, it can be considered as a congenital nevus caused by hyperpigmentation, etc., and generally does not need to be treated. 2. If there is frequent masturbation and other habits, as well as the foreskin for a long time by the underwear friction, the existence of the foreskin glansitis lead to inflammatory stimulation, etc., may lead to the deposition of melanin, the appearance of black plaques. 3. In addition, we cannot rule out the existence of HPV virus infection due to unclean sex and other behaviors, resulting in the appearance of black plaques or black cauliflower-like swelling. Therefore, it is recommended to go to the hospital for further examination to clarify the cause of the disease and timely treatment.