In 1956 it has been reported by Professor C.D.Campbell of Washington State University, U.S.A. and Professor S.K.Runcorn of King's College, University of Durham, England that about a half of Columbia River Tertiary basalt flows of Washington State, U.S.A. show the reversly magnetized direction of the natural remanent magnetizations. However, the stability of these remanent magnetizations had not been examined yet. In this paper, the present author has described a preliminary experimental work of rock magnetism on these flows. This work has mainly been done in order to examine the magnetic stability of those basalt specimens. More than three hundred cored plug specimens of Columbia River basalts which are cylindrical having 1 inch diameter and 7/8 inches of height were submitted by Professor Campbell to the present author. The following set of measurements was carried out during 1962 and 1963 at Geophysics Laboratory of the University of Toronto, Canada, and some statistical treatments for these data were added after coming back to Yamaguchi University. 1) Measurement of the original remanent magnetization, 2) Storage test under the present geomagnetic field, 3) Alternating current demagnetization. Unfortunately, the present author has not been given any information about the reference orientations of the plug specimens relatively to the present geomagnetic field. Without these, the magnetic history of those specimens cannot be discussed in detail.However the lack of such informations gives significant difficulty, each specimen has a datum of direction of the natural remanent magnetization refered to the present geomagnetic field obtained first by the Campbell's school. This is available to be a help. The present author has been able to rearange these data.