To get actual response spectra of quantum type photodetectors from measured photo-current spectra using FTIR method, two feasible and convenient correction schemes of calculated instrument function scheme and standard detector transfer scheme are proposed. The feasibility, limitations and matters which need attention are discussed in detail. Based on those schemes, consistent response spectra of various shortwave infrared InGaAs photodetectors have been gained. A comparison has been made to the response spectrum measured using a precisely calibrated grating monochromator system and the validity of the schemes is confirmed.