Small black spots on the foreskin can be caused by factors such as frequent masturbation, prepuce glans inflammation, infectious diseases and melanin deposition. 1. Frequent masturbation: frequent masturbation can lead to an increase in the penis, glans and other parts of the infection, frequent masturbation activities can lead to excessive friction of the foreskin, easy to lead to local melanin deposits, the performance of small black spots. 2. circumcision: inflammation of the glans and prepuce, can stimulate the local skin breakage, easy to form small black spots like lesions. 3. Infection of sexually transmitted diseases: unclean sex can lead to infection of sexually transmitted diseases, mainly on the penis, glans, foreskin and other parts of the infringement, the condition of the progression or after treatment may be localized black spots and other manifestations. 4. melanin precipitation: underwear size is too tight, can lead to the foreskin long-term friction by the underwear, can lead to localized melanin precipitation, and the appearance of black spots. When there are small black spots on the foreskin, you need to consult a doctor in time, under the guidance of a specialist to actively carry out appropriate treatment, which will help to alleviate the discomfort symptoms as soon as possible.