The invention provides a method for producing a silicon oxide film, whereby a film having uniform optical constants such as refractive index, absorption coefficient, etc. can be formed continuously at a high deposition rate. A method for producing a silicon oxide film, which comprises depositing a silicon oxide film on a substrate by carrying out AC sputtering by using a sputtering target comprising silicon carbide and silicon with a ratio in number of atoms of C to Si being from 0.5 to 0.95, in an atmosphere containing an oxidizing gas, with an alternating current having a frequency of from 1 to 1,000 kHz.