A hundred Quaternary basalt samples ware collected at the eastern part of the northern district of Yamaguchi Prefecture, west Japan. These natural remanent magnetizations (NRM) were measured. And those were submitted to thermo-magnetic (Js-T) analysis. Most of all samples examined show the normal NRM and few reversed and obliques are also found, However, the reversed NRM have been recognized only in lower Pleistocene. The Js-T analysis on these samples shows remarkable difference between normally and reversely magnetized rocks