A polarization image processing apparatus includes an illumination unit, a splitter, first and second polarization imaging devices, and a processing unit. The illumination unit illuminates a first surface of a transparent or translucent object with first illumination light polarized in a first direction and second illumination light polarized in a second direction, which crosses the first direction, alternately. Illumination axes of the first illumination light and second illumination light substantially coincide with an imaging axis of the polarization image processing apparatus. The splitter divides returning light into at least two light components. The first and second polarization imaging devices receive the light components. The processing unit detects a condition of a second surface of the object on the basis of first and second polarization images obtained by the first polarization imaging device and third and fourth polarization images obtained by the second polarization imaging device.