A valve stem seal comprising: a reinforcement ring having a tubular body section; and a rubber-like elastic body which is integrally provided with the reinforcement ring, the valve stem seal being configured to be fixed to a valve stem guide that guides a valve stem, wherein the rubber-like elastic body includes: a seal section which is slidable on the valve stem; and a fitting section which is provided on an inner peripheral surface of the body section and which is configured to be fitted and fixed to the valve stem guide, and an inner peripheral surface of the fitting section is provided with a plurality of annular seal protrusions (25, 26), each including a first inclined surface (25a, 26a) having a diameter that increases from a radially inward tip toward the seal section and a second inclined surface (25b, 26b) having a diameter that increases from the radially inward tip toward a side opposite to the seal section, characterized in that a first seal protrusion which is closest to the seal section is configured so that an inclination of the second inclined surface is smaller than that of the first inclined surface, and a second seal protrusion which is farthest from the seal section is configured so that an inclination of the first inclined surface is smaller than that of the second inclined surface. a reinforcement ring having a tubular body section; and a rubber-like elastic body which is integrally provided with the reinforcement ring, the valve stem seal being configured to be fixed to a valve stem guide that guides a valve stem, wherein the rubber-like elastic body includes: a seal section which is slidable on the valve stem; and a fitting section which is provided on an inner peripheral surface of the body section and which is configured to be fitted and fixed to the valve stem guide, and an inner peripheral surface of the fitting section is provided with a plurality of annular seal protrusions (25, 26), each including a first inclined surface (25a, 26a) having a diameter that increases from a radially inward tip toward the seal section and a second inclined surface (25b, 26b) having a diameter that increases from the radially inward tip toward a side opposite to the seal section, characterized in that a seal section which is slidable on the valve stem; and a fitting section which is provided on an inner peripheral surface of the body section and which is configured to be fitted and fixed to the valve stem guide, and an inner peripheral surface of the fitting section is provided with a plurality of annular seal protrusions (25, 26), each including a first inclined surface (25a, 26a) having a diameter that increases from a radially inward tip toward the seal section and a second inclined surface (25b, 26b) having a diameter that increases from the radially inward tip toward a side opposite to the seal section, characterized in that a first seal protrusion which is closest to the seal section is configured so that an inclination of the second inclined surface is smaller than that of the first inclined surface, and a second seal protrusion which is farthest from the seal section is configured so that an inclination of the first inclined surface is smaller than that of the second inclined surface.