We study the relation between the abelian monopole condensation and the deconfinement phase transition of the finite-temperature pure QCD, and find that the expectation value of the Polyakov loop becomes zero when a long monopole loop is distributed uniformly in the configuration of the confinement phase as suggested in the previous Monte-Carlo simulations, whereas this value becomes non-zero when the long monopole loop disappears in the deconfinement phase. We also discuss the relation between the monopole picture and the spontaneous breaking of Z(N) symmetry that is the usual interpretation of the deconfinement transition in the finite-temperature SU(N) gauge theory.