  We study the correlation between confinement and dynamical chiral-symmetry
breaking (D$\chi$SB) in the dual Ginzburg-Landau (DGL) theory using the
effective potential formalism. The DGL theory is an infrared effective theory
based on the dual Higgs mechanism, and provides the nonperturbative gluon
propagator, which leads to the linear quark potential. The screening effect for
the confining potential can be obtained by introducing the infrared cutoff
corresponding to the hadron size. We formulate the effective potential for
D$\chi$SB in the DGL theory, and find the vacuum instability against quark
condensation. To extract confinement effect, we separate the effective
potential into the confinement part and others by dividing the confinement term
from other terms in the gluon propagator in the DGL theory. The confinement
part provides the dominant contribution to D$\chi$SB, which is regarded as
monopole dominance for D$\chi$SB. The relevant energy for D$\chi$SB is found to
be the infrared region below 1GeV. Monopole dominance for the DGL propagator is
also found in the intermediate region, 0.2fm $\simle r \simle$ 1fm.

High Energy Physics - Phenomenology