A survey has been carried out on the characteristics of propagation of slight atmospheric pressure changes concerning the seiches which developed in wide areas in Kyushu and the western part of The Sea of Japan in February and July in 2009. The typical propagation direction of slight atmospheric pressure changes is eastward and the typical propagation speed is 2 km/min. When slight atmospheric pressure changes develop, they do not develop just once. Some components of various frequencies with different propagation speeds come over repeatedly. From the dispersion relation equation of atmospheric gravity waves, the vertical propagation speed is estimated to be about 1/10 of horizontal one.
