We studied the dependent factors for improving spectral resolution and signal-to-noise ratio (SNR) in a spatially modulated Fourier transform spectrometer comprised of a Wollaston prism. The obtainable spectral resolution was investigated for the factors such as the ratio of overlapped to nonoverlapped sectors in a focal plane, SNR, and the maximum optical path difference. The accurate application of signal padding for the interferogram was effective in obtaining better spectral resolution and SNR in the spatially modulated Fourier transform spectrometer based on the Wollaston prism, for which it is difficult to have adequate optical path difference. We investigated the change of spectral resolution and shape for the measured and signal padded interferograms of the 6382  cm^−  1 center wavenumber light source. The best obtainable spectral resolution was drastically improved to 27  cm^−  1, whereas the SNR was improved up to 12 times compared to that of the not signal padded.