Dual Lattice Blockspin Transformation and Monopole condensation in QCD

Recent studies of confinement based on the idea of abelian monopole condensation are reviewed briefly. Emphasis is placed on the approach to get the effective monoole action using the blockspin transformation on the dual lattice. The trajectory obtained looks to be the renormalized one in $SU(2)$ QCD. A disorder parameter of confinement is constructed. Monopole condensation occurs also in $SU(3)$ QCD.