Rayleigh lidar observations of the molecule density in the upper stratosphere and the lower mesosphere using an XeF laser (351 and 353 nm) where made from April 1985 through March 1986, at Fukuoka, Japan (33.6¿N, 130.4¿E). The observed density profiles show that existence of waves with wavelengths around 10 km and downward phase velocities between about 0 and 1.2 km/h. In more than half of the cases, the induced wave periods are longer than the inertial period. Analysis shows that the zonal phase velocities of the waves go in the direction opposite to that of the background flow, at least in these cases. The phase velocity and amplitude of the waves show a semiannual variation. The height dependence of the averaged fluctuation amplitude indicates that the energy dissipation of the waves occurs in the observed altitude range.