Provided is a method of manufacturing a glass product including the following steps. An intermediate glass product is provided. A portion of the intermediate glass product is heated to a predetermined temperature. A tool and the heated portion of the intermediate glass product are brought into contact. Under a state that a tool contacts the heated portion, at least one of the tool and the intermediate glass product is rotated so that the tool and the intermediate glass product relatively rotate, wherein a part of the tool that contacts the heated portion comprises or is made of glassy carbon.