The results of the three-dimensional (3D) self-consistent simulations of a 14 GHz minimum-B electron cyclotron resonance ion source plasma obtained upon 1.8×104 microwave periods by the particle-in-cell code are reported. The initial density of plasma contained in a chamber of 24 cm length and 6.3 cm in diameter is 0.6×1012 cm−3. We have used the explicit Boris-leap-frog scheme on the three-dimensional computer grid of 32×32×64 size. The results of the relativistic simulations show that the confined plasma has a complex spatial structure with a zone of periodic bounce oscillations as well as areas where banana trajectories are observed. The obtained electron energy distribution function makes it evident that in the electron cyclotron resonance minimum-B plasma there coexist three separable electron groups: a group of cold electrons with the energy up to 80 eV, a group of hot electrons whose energy extends to 80 keV, and a group of superhot electrons accelerated up to hundreds of kilo-electron volts. The space distributions of plasma ions have been found.