1. A polarization-sensitive optical image measuring system equipped with a polarization-sensitive optical image measuring unit, as well as a computer installed with a program for processing an image data obtained by the polarization-sensitive optical image measuring unit, the polarization-sensitive optical image measuring system characterized in that the computer has an input device, an output device, a CPU, and a storage device, and functions, according to the program, as: a means for processing noise-containing OCT signals obtained by measuring a sample using a birefringence calculation algorithm, to obtain measured birefringence values representing birefringence values measured in a presence of noise; a means for statistically adjusting the noise using Monte Carlo calculations and then processing said noise with the algorithm, and repeating this process to simulate a measured birefringence distribution to determine noise characteristics of measured birefringence values; a means for repeating the Monte Carlo calculations by assuming different values for noise level and true birefringence value, respectively, to form three-dimensional histogram information showing how frequently a combination of given true birefringence value, SN ratio, and measured birefringence value appears; a means for assuming specified measured birefringence values and SN ratios from the three-dimensional histogram information to take out a true birefringence probability density distribution; and a means for estimating true birefringence values from the true birefringence probability density distribution.