The purpose of the present invention is to provide: a synthetic amorphous silica powder which is suitable as a raw material for a synthetic silica glass product used in a high-temperature and reduced-pressure environment, which can yield a synthetic silica glass product such that the occurrence or expansion of air bubbles in the glass product is inhibited even in use in a high-temperature and reduced-pressure environment, and which can be obtained at a relatively low cost; and a process for manufacturing the same. A synthetic amorphous silica powder obtained by subjecting silica as raw material to granulation and firing, characterized in that (1) the particle diameter (DV50) at a cumulative frequency of 50% in the volume particle size distribution, (2) the cumulative frequency of particles having volume diameters of 45[mu]m or less, (3) the value (DV90-DV10)/DV50 obtained by dividing the difference between the particle diameter (DV90) at a cumulative frequency of 90% in the volume particle size distribution and the particle diameter (DV10) at a cumulative frequency of 10% therein by the particle diameter (DV50) at a cumulative frequency of 50% therein, (4) the FNL/FNS ratio of the frequency (FNL) of a frequency peak in the number particle size distribution to the frequency (FNS) of a frequency peak in the region of particle diameters of 30[mu]m or less in the number particle size distribution, and (5) the bulk density are within prescribed ranges respectively.