PURPOSE: To obtain high-purity foamless hollow synthetic quartz article, by making a gas flow into a hollow part continuously, heating the end part of the hollow quartz glass article, introducing a volatile silicon compound shown by the formula RnSiX4-n into it.

CONSTITUTION: The high-frequency plasma flame 12 or oxyhydrogen flame is blown to the top of the quartz glass 1 having the hollow part 2, so that the end part of the quartz glass article 1 is heated. A mixed gas of a volatile silicon compound shown by the formula RnSiX4-n (R is hydrogen or monofunctional alkyl group; X is chlorine or fluorine; n is 0W4) is fed from the raw material feed pipe 13 to the end of the glass article 1. The raw material is decomposed, and grown as the quartz layer 14 on the glass article 1. An inert gas is sent to the hollow part of the glass article 1 continuously during the operation.