Broad band records of Macquarie Ridge earthquake of May 1989 recorded in Japan show anomalous propagation of Rayleigh wave with frequency of 5--25 mHz along the back arc side of the Izu-Mariana trench. Rayleigh waves at three stations in central Japan show different polarization, that is, while one station shows a normal Rayleigh wave, the other two stations, only 290 and 510 km apart, show anomalous polarization with a large deviation from the radial direction and their temporal and gradual change. Possible causes of this anomaly include anisotropy as well as laterally heterogeneous velocity structure of the upper mantle in this active marginal basin region. ¿ American Geophysical Union 1992