The play back system of digital video signal which transfers the information stored in magnetic tapes to garnet film and reads out it magneto-optically is being developed. To put the system to practical use, it is expected that the signal recorded with wavelength of shorter than 0.8μm is read out with sufficient carrier-to-noise ratio (CNR). We confirmed that it was possible to read out a signal with wavelength of 0.77μm experimentally and analytically as well. To achieve a good CNR we measured spectra of readout signal by using a transfer readout exerciser. On the bases of a series of experiments, we found that dominant noise was polarized noise due to granularity of magnetic tape. By elongating the readout spot in the direction of recorded track width by three times that of normal, improvement of CNR more than 10 dB was obtained.