  We study the relation between the abelian monopole condensation and the
deconfinement phase transition of the finite-temperature pure QCD. The
expectation value of the monopole contribution to the Polyakov loop becomes
zero when a long monopole loop is distributed uniformly in the configuration of
the confinement phase. On the other hand, it becomes non-zero when the long
monopole loop disappears in the deconfinement phase. We also discuss the
relation between the monopole behaviors and the usual interpretation of the
spontaneous breaking of Z(N) symmetry in finite-temperature SU(N) QCD. It is
found that the boundary condition of the space direction is important to
understand the Z(N) symmetry in terms of the monopoles.
