A mold for earpiece devices either to connect an earphone to the ear canal or to act as a cover or plug thereof, allowing to prevent the development of ear diseases comprising: a mold placed in the ear canal and/or ear shell, adjusted to its shape, and whose external border is in direct contact with the user's skin; and a metallic piece with biocide properties, located inside the mold at a distance close to the border thereof; wherein the metallic piece is adjusted from inside the mold (10) to the shape of the external contour thereof, allowing that only the mold is in direct contact with the skin, and encompassing all the zones where contact is produced.