An artificial nipple, which is a molded product made of an elastic material such as a soft resin and configured overall as a substantially conical hollow body, the artificial nipple comprising: a base section that widens to match an attachment object; an areola section that is formed contiguously to the base section and that extends while narrowing gradually; and a nipple section that extends from the areola section and that narrows more than the areola section, the artificial nipple further comprising: a flange section provided in the base section and having a predetermined thickness; a check valve formed with a valve body so as to be entirely accommodated within a thickness dimension of the flange section; and a bulge section that is integrally formed below the areola section, and that bulges outward in a radial direction; and the flange section which opposes an overhang-like lower face of the bulge section, across a constricted section, wherein an inward-facing flange section of a hard cap with which the artificial nipple is intended to be used and that can be fitted to a bottle for containing a beverage enters into the constricted section such that the cap becomes attached, and a depth of at least part of the constricted section is set to be further back than an inner end of the inward-facing flange section, as a result of which a gap is formed between the part of the constricted section and the cap, and wherein the check valve is provided at a position at which the check valve communicates with the gap, characterized in that a through-hole extends up and down through the bulge section at a position immediately above the check valve, the inner end of the through-hole stands slightly further inward than the inward-facing flange section of the cap, when fitted, so that a further gap is formed which communicates with the gap formed between the part of the constricted section of the artificial nipple and the cap. a base section that widens to match an attachment object; an areola section that is formed contiguously to the base section and that extends while narrowing gradually; and a nipple section that extends from the areola section and that narrows more than the areola section, the artificial nipple further comprising: a flange section provided in the base section and having a predetermined thickness; a check valve formed with a valve body so as to be entirely accommodated within a thickness dimension of the flange section; and a bulge section that is integrally formed below the areola section, and that bulges outward in a radial direction; and the flange section which opposes an overhang-like lower face of the bulge section, across a constricted section, wherein an inward-facing flange section of a hard cap with which the artificial nipple is intended to be used and that can be fitted to a bottle for containing a beverage enters into the constricted section such that the cap becomes attached, and a depth of at least part of the constricted section is set to be further back than an inner end of the inward-facing flange section, as a result of which a gap is formed between the part of the constricted section and the cap, and wherein the check valve is provided at a position at which the check valve communicates with the gap, characterized in that a through-hole extends up and down through the bulge section at a position immediately above the check valve, the inner end of the through-hole stands slightly further inward than the inward-facing flange section of the cap, when fitted, so that a further gap is formed which communicates with the gap formed between the part of the constricted section of the artificial nipple and the cap. a flange section provided in the base section and having a predetermined thickness; a check valve formed with a valve body so as to be entirely accommodated within a thickness dimension of the flange section; and a bulge section that is integrally formed below the areola section, and that bulges outward in a radial direction; and the flange section which opposes an overhang-like lower face of the bulge section, across a constricted section, wherein an inward-facing flange section of a hard cap with which the artificial nipple is intended to be used and that can be fitted to a bottle for containing a beverage enters into the constricted section such that the cap becomes attached, and a depth of at least part of the constricted section is set to be further back than an inner end of the inward-facing flange section, as a result of which a gap is formed between the part of the constricted section and the cap, and wherein the check valve is provided at a position at which the check valve communicates with the gap, characterized in that a through-hole extends up and down through the bulge section at a position immediately above the check valve, the inner end of the through-hole stands slightly further inward than the inward-facing flange section of the cap, when fitted, so that a further gap is formed which communicates with the gap formed between the part of the constricted section of the artificial nipple and the cap.