Near-infrared (NIR) spectroscopic imaging technique enables to chemically identify materials by collecting NIR absorption or reflection spectra at each pixel in areas of interest, so that it has been applied for monitoring pharmaceutical, biochemical, food, agricultural and other processes. The technique is also promising for monitoring various chemical changes according to the progress of reaction, degradation, dissolution, crystallization etc. in various polymer processing processes. On the other hand, NIR light is applicable to monitoring optical properties of polymer products such as birefringence because of the small absorption coefficient. We developed an advanced NIR spectroscopic imaging technique for measuring simultaneously the two-dimensional images of NIR absorption spectra and birefringence in polymeric materials. This method enables to determine the birefringence as well as the changes of chemical component and sample thickness from NIR absorption spectrum. In this study, the proposed imaging technique was applied for visually analyzing injection molded polystyrene (PS) products. The retardation, which is the product of sample thickness and birefringence, and the azimuth direction of slow axis were calculated from polarized NIR spectra at each pixel. The two-dimensional image of flow direction was visualized with the azimuth image of slow axis. The retardation decreased as the measured position became far from the gate in one injection molded PS sample. The retardation averagely decreased in the PS samples fabricated with high injection speed or high cylinder temperature.