The main objective of this study is to clarify the relation between the consistency and the viscosity of soft clay. The soft clay can be considered as structual viscosity fluid. The consistency and viscosity were measured by using a variety of consistency tests and rehological tests. It was revealed that the relationship between FC value or Ff value and liquid limit was liniar. The yield value and the plastic viscosity were mesured by a rotational visco-meter. It was clealy seen that relationships between the yield value or the plastic viscosity and flowing time had a liniar correlation.