This paper presents a case study on the liquefaction potential both of the sand layers where the liquefaction was observed after the 1973 Neumurohanto-Oki Earthquake, the 1978 Miyagiken-Oki Earthquake and the 1983 Nipponkai-Chubu Earthquake and those where the liquefaction was not observed around the liquefied sites.
　The in-situ cyclic shear strength ratio R is evaluated from the results of the cyclic triaxial test with undisturbed samples. On the other hand, the in-situ cyclic shear stress ratio L is calculated by the computer program SHAKE.
　The applicability of the so-called detailed evaluation method for the liquefaction potential is discussed in terms of the ratio Fl defined as R/L.