Abstract: A cup, a mold and an underwear are disclosed. The cup includes an upper surface layer, a lower surface layer and a nipple-exposure prevention layer. The upper surface layer is provided with an inner concave portion, the nipple-exposure prevention layer is arranged in the inner concave portion, and the upper surface layer is arranged towards a side far away from a breast. When the lower surface layer of the cup is closely attached to the upper surface layer, and the lower surface layer is contacted with a nipple, the nipple-exposure prevention layer is capable of preventing a nipple on a female breast from being prominent.