Experiments on the formation of a high-pressure pulse in a solid under the action of a high-power (up to 3 TW/m2) pulsed (8 μs) flow of 0.8-MeV relativistic electrons and hot plasma have been performed. A technique for measuring a high pulsed pressure from the shift of the R1 (694.23-nm) and R2 (692.8-nm) ruby fluorescence lines has been developed. The minimum pressure that can be measured by the developed instrument is 0.1 kbar. The pressure measured in experiments on the interaction of an electron beam and hot plasma with a surface reached 1.1 kbar, which is in good agreement with the calculation results. It is revealed that the X rays induced by the electron beam are quite intense enough to excite ruby fluorescence, which allows measurements to be performed without pumping the R1 and R2 lines by external radiation.