  To find a perfect lattice action in terms of monopole action on the dual
lattice, we performed simulations of a monopole effective action obtained
numerically from vacuum configurations in SU(2) QCD. Although the Polyakov loop
behavior near $T_c$ is well reproduced by the action, a small but repulsive
term is needed in addition to get the string tension correctly. It is reported
also a monopole effective action in $SU(3)$ QCD which is expressed by one kind
of monopole currents.
