  On the basis of perturbative QCD and the relativistic quark model we
calculate relativistic corrections to the double $\eta_c$ meson production in
proton-proton interactions at LHC energies. Relativistic terms in the
production amplitude connected with the relative motion of heavy quarks and the
transformation law of the bound state wave functions to the reference frame of
moving charmonia are taken into account. For the gluon and quark propagators
entering the amplitude we use a truncated expansion in relative quark momenta
up to the second order. Relativistic corrections to the quark bound state wave
functions are considered by means of the Breit-like potential. It turns out
that the examined effects decrease total nonrelativistic cross section more
than two times and on 20 percents in the rapidity region of LHCb detector.
