The strength of fresh rocks and altered rocks, including hydrothermally altered or weathered rocks, is generally evaluated based on uniaxial compressive strength(UCS).However, rock corepieces for UCS tests cannot always be obtained from outcrops of faulted or cracked rock masses. Inthese cases, the point load strength(PLS)test is a convenient and effective alternative to the UCS test, because it can be done promptly using on-site testing equipment with various shaped small rock specimens taken from outcrops or floats.Provided that we can calculate a UCS estimate from a PLS value, the PLS test can lead more convenient and cheaper.Many researchers have already studied the relationship between the PLS and UCS. However, they could not be said that these studies have clarified the relationship between the PLS and UCS of soft rocks. Recearchers. However, there were very few reports about the relationships of soft rocks.....