The invention relates to a breast cap part for a breast pump, which is disposed on an areola of a female breast when used. The breast cap includes a truncated base body (1) having a large rear opening (13) and a small front opening (14), the base body being embodied in order to receive a breast cap (6) in a funnel. The truncated base body (1) is at least partially made of a heat accumulating and/or heat conducting material and is heated when required. The heating does not exclusively occur when the body temperature of the female breast is transmitted. Other means for heating the breast cap part are used.