We analyze high quality digital waveform data at stations in Japan from the POSEIDON and IRIS broad-band seismograph networks. The analysis of multiple ScS waves of the deep event beneath Sakhalin on 12 May 1990 shows that the orientation of the principal axis of horizontal ScSn particle motion is rotated clockwise from NWN-SES to N-S as the number of reflections increases. This suggests that the attenuation of the E-W component is higher than that of the N-S component of ScS waves. The spectral ratio ScS2/ScS1 differs between the two horizontal components. We estimate the quality factor QScS of the whole mantle for each horizontal component using the decay rate of spectral ratio of band-passed ScS1 and ScS2 phases in the frequency range from 0.01 to 0.03 Hz. We obtain a higher average QScS for the N-S component (141¿8) than that for the E-W component (91¿5). That is, the E-W component attenuates more than the N-S component. For upcoming ScS waves in the N-S direction is nearly parallel to the strike of the subducting slab beneath the mantle wedge in the Japanese islands, and the E-W is perpendicular to the strike. The up-welling and downgoing flow in the mantle wedge due to drag caused by the subduction is likely to cause the difference in attenuation between the two directions, in other words, azimuthal attenuation anisotropy. ¿ American Geophysical Union 1995