Black spots on hands are considered to be caused by age spots, solar keratosis, melanoma and other reasons. 1. Age spots: age spots are also called seborrheic keratosis, the cause of which is not particularly unclear, but it is considered to be related to ageing and skin aging, mainly manifested as plaques of varying sizes, which may be of normal skin color, or may be light brown or even black. 2. Solar keratosis: solar keratosis is also called senile keratosis, common in middle-aged and elderly men, and sun exposure has a certain relationship, mainly manifested as brown keratotic plaques, the surface is also covered with not easy to peel off the black-brown scales, this disease has a certain tendency to malignant changes. 3. Melanoma: Melanoma is a kind of tumor with high malignant degree, which is mainly caused by malignant change of melanocytes, and the early performance is that the original nevus rapidly increases and bulges, and the color change occurs. There may be other reasons for the black spots on the hands, it is recommended to go to the regular hospital in time, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.