Pumping tests on ultra-high-strength concrete of 150 MPa were conducted to examine changes in its performance due to pumping while in the fresh state and after hardening. The following was found: (1) After pumping, the inverted slump-cone time of ultra-high-strength con - crete of 150 MPa tended to be shorter than before pumping. It was concluded that certain changes occurred in the mortar phase during pumping, since its plastic viscosity was found to decrease after pumping when tested using a rotor blade viscometer. (2) No significant difference was recognized between the performances of hardened concrete before and after pumping in the scope of this experiment. (3) The pressure loss during pumping of concrete with a low-water-binder ratio was more strongly influenced by the plastic viscosity than by the yield value. (4) The pressure loss of ultra-high-strength concrete has a rough correlation with the product of the calculated plastic viscosity and the pumping rate.