  The Nambu--Jona-Lasinio model is investigated in the $1/N_c$ expansion with
the dimensional regularization. At the four-dimensional limit the meson
propagators have simple forms in the leading order of the $1/N_c$ expansion.
Thus the next to leading order calculation reduces to an ordinary one loop
calculation. Here we obtain an explicit form of the $1/N_c$ correction and
numerically evaluate the $N_c$ dependence for the gap equation.
