A multiple regression analysis method is applied to detect anomalous changes of ground water level due to earthquakes. Corrected water level is calculated by eliminating responses due to barometric pressure, earth tide and precipitation from the observed water level based on a model obtained by the minimum AIC (Akaike Information Criterion) procedure. The data observed at Haibara well, Shizuoka, central Japan during the period from Feb. 1981 to Dec. 1990 is analyzed using this method. It is shown that the corrected water level decreases more than 1 cm after each of fifteen earthquakes. ¿ American Geophysical Union 1992