  We study properties of effective temperature of non-equilibrium steady states
by using the anti-de Sitter spacetime/conformal field theory (AdS/CFT)
correspondence. We consider non-equilibrium systems with a constant flow of
current along an electric field, in which the current is carried by both the
doped charges and those pair created by the electric field. We find that the
effective temperature agrees with that of the Langevin systems if we take the
limit where the pair creation is negligible. The effect of pair creation raises
the effective temperature whereas the current by the doped charges contributes
to lower the effective temperature in a wide range of the holographic models.
