Method of molding glass body

A method of molding a glass body, comprising the steps of:

• placing a glass preform between upper and lower molds of a mold assembly, the upper and lower molds being located opposite each other;
• heating the mold assembly and glass preform to a predetermined heating temperature falling within a heating temperature range corresponding to a glass viscosity range of the glass preform of 10.sup.8 to 10.sup.10.5 poise;
• applying a pressure high enough to mold the glass preform between the upper and lower molds when the glass preform is heated at the predetermined heating temperature, so that an unfinished glass molded body is formed from the glass preform;
• releasing the pressure after the pressurization for a predetermined period of time at the predetermined temperature and gradually cooling the unfinished glass molded body and the mold assembly to a predetermined cooling temperature falling within a cooling temperature range corresponding to a glass viscosity range of 10.sup.11.5 to 10.sup.14 poise while the unfinished glass molded body is held in a ring holder in the mold assembly;
• releasing a glass molded body with the ring holder from the mold assembly;
• placing the next glass preform held in the ring holder and kept in the temperature range between the room temperature and 300 degrees between the upper and lower molds of the mold assembly kept in a temperature range between the predetermined cooling temperature and the predetermined heating temperature, the difference between the said predetermined cooling and heating temperature being within the range of 20 degrees C. to 150 degrees C.;
• and performing steps of heating, pressure-applying, pressure releasing, cooling, and releasing of the glass molded body, in a single heating chamber whereby glass molded bodies are provided continuously by supplying glass preform continuously.