In cosmic rays, the GZK cutoff is suggested to be between 50 EeV and 60 EeV, with observationally 57 EeV (HiRes, Pierre Auger Observatory) and theoretically and observationally 56 EeV being suggested as the representative value. In previous study, it was drawn that up, charm, and top quarks consist of inner boson particles located on 10D, 11D, and 12D and shell fermion particles located on 4D, 5D, and 6D, and their masses were calculated in detail. After plotting the log values of the calculated masses on 10D, 11D, and 12D and drawing its parabola, the masses on 3D are calculated to be 50.60 EeV in kinet-ic state, 60.82 EeV in steady state, and 56.94 EeV in combined state, which are consistent with the results of GZK cutoff. The above calculation is the property of space itself, which has nothing to do with supernova explosion, black hole jet, etc. In previous study, we argued that hydrogen is continuously generated in space. The above result implies that ultra-high-energy cosmic rays are the particles that suddenly appear at a cosmic void of 3D space from high dimensions.