  We study SU(3) gluon electric and magnetic masses at finite temperatures
using quenched lattice QCD on a $20^2 \times 32 \times 6$ lattice. We focus on
temperature regions between $T=T_c$ and $6T_c$, which are realized in BNL
Relativistic Heavy Ion Collider and CERN Large Hadron Collider experiments.
Stochastic quantization with a gauge-fixing term is employed to calculate gluon
propagators. The temperature dependence of the electric mass is found to be
consistent with the hard-thermal-loop perturbation, and the magnetic mass has
finite values in the temperature region of interest. Both screening masses have
little gauge parameter dependence. The behavior of the gluon propagators is
very different in confinement/deconfinement physics. The short distance
magnetic part behaves like a confined propagator even in the deconfinement
phase. A simulation with a larger lattice, $32^2 \times 48 \times 6 $, shows
that the magnetic mass has a stronger finite size effect than the electric
mass.
