In Ca(NbO3)2 crystals a depolarization current is obtained in short-circuit measurements by light irradiation at 90 K after application of an external electrical field at cooling down. The spectral response of this current shows a broad band over the whole visible wavelength range. The position and height of the current maximum depend on the amount and direction of the spectral scanning speed. Since the short-circuit current is assumed to be associated with the rate of heterocharge neutralization by the drift of photo-excited carriers these phenomena are discussed in the model of persistent internal polarization rather than in that of moving zero-field plane. The results of calculation show good agreement with the experimental data.