  Two of recent progress in lattice QCD approach to nuclear force are reported.
(i) Tensor force from quenched lattice QCD: By truncating the derivative
expansion of inter-nucleon potential to the strictly local terms, we obtain
central force V_C(r) and tensor force V_T(r) separately from s-wave and d-wave
components of Bethe-Salpeter wave function for two nucleon state with J^P=1^+.
Numerical calculation is performed with quenched QCD on 32^4 lattice using the
standard plaquette action at beta=5.7 with the standard Wilson quark action
with kappa=0.1640, 0.1665, 0.1678. Preliminary results show that the depths of
the resulting tensor force amount to 20 to 40 MeV, which is enhanced in the
light quark mass region. (ii) Nuclear force from 2+1 flavor QCD with PACS-CS
gauge configuration: Preliminary full QCD results are obtained by using 2+1
flavor gauge configurations generated by PACS-CS collaboration. The resulting
potential has the midium range attraction of about 30 MeV similar to the
preceding quenched calculations. However, the repulsive core at short distance
is significantly stronger than the corresponding quenched QCD result.
