PURPOSE: To make it possible to produce high-quality quartz glass in a short time, by heating dry gel prepared from an alkyl silicate as a raw material to a given temperature by the sol-gel method, maintaining the gel in d dryer at a specific temperature and successively sintering.

CONSTITUTION: Dry gel prepared by using at least an alkyl silicate as a raw material is heated to ≥300°C, dehydrated and decarbonized. Then the dry gel is set in a vacuum furnace, made into glass under reduced pressure to synthesize quartz glass. In this sol-gel method, the dry gel is heated to ≥300°C to carry out dehydration and decarbonization but the dry gel has ability to adsorb water in air until pore closing finished even if dehydration and condensation are advanced. Therefore the dry gel heated to ≥300°C is maintained in the dryer in an atmosphere at ≥30°C showing dehydrating effect. Then the dry gel is taken out from the dryer and successively made into glass in a vacuum furnace.