An object of the invention is to provide a process for producing a synthetic quartz glass while taking account of a refractive index distribution remaining in the synthetic quartz glass; a jig for use in the synthetic-quartz-glass production process; and a synthetic quartz glass for an optical member, produced by the process. A process for producing a synthetic quartz glass, which comprises: depositing and growing fine quartz glass particles synthesized by flame hydrolysis of a glass-forming material on a rotating target to thereby form a porous quartz glass base of a substantially cylindrical shape; presintering the porous quartz glass base; and heating the presintered porous quartz glass base to a temperature not lower than the vitrification temperature to convert the base into a transparent glass, wherein in the step of conversion into a transparent glass, the porous quartz glass base is placed so as to make its growth axis vertical and a load is vertically imposed on the thus-placed porous quartz glass base.