PURPOSE: To enable various measurements, by using a main drive shaft connected to a motor and two auxiliary drive shafts connected to said main drive shaft through a differential mechanism to compare and measure reference load with load to be measured.

CONSTITUTION: Torque T1 transmitted to a main drive shaft 2 from a motor 1 is transmitted to auxiliary drive shafts 4, 5 from a differential mechanism 3 in an equally distributed state. The container 38 of the auxiliary drive shaft 4 is filled with reference load having known viscosity and the container 39 of the auxiliary drive shaft 5 is filled with a specimen. The rotary speeds of each auxiliary drive shafts 4, 5 are measured by rotary speed meters 36, 37 and power consumption is measured by a dynamometer 35. As the reference load, one of which the viscosity is changed with the elapse of time is used and, when a mixture prepared by mixing sand or gravel in a cement paste is used as the specimen, a viscosity ratio can be detected by calculating the influence of sand or gravel from the inverse number of a rotary speed ratio.