  The first lattice QCD result on the nuclear force (the NN potential) is
presented in the quenched level. The standard Wilson gauge action and the
standard Wilson quark action are employed on the lattice of the size 16^3\times
24 with the gauge coupling beta=5.7 and the hopping parameter kappa=0.1665. To
obtain the NN potential, we adopt a method recently proposed by CP-PACS
collaboration to study the pi pi scattering phase shift. It turns out that this
method provides the NN potentials which are faithful to those obtained in the
analysis of NN scattering data. By identifying the equal-time Bethe-Salpeter
wave function with the Schroedinger wave function for the two nucleon system,
the NN potential is reconstructed so that the wave function satisfies the
time-independent Schroedinger equation. In this report, we restrict ourselves
to the J^P=0^+ and I=1 channel, which enables us to pick up unambiguously the
``central'' NN potential V_{central}(r). The resulting potential is seen to
posses a clear repulsive core of about 500 MeV at short distance (r < 0.5 fm).
Although the attraction in the intermediate and long distance regions is still
missing in the present lattice set-up, our method is appeared to be quite
promising in reconstructing the NN potential with lattice QCD.
