  Using the Dirac-mode expansion method, which keeps the gauge invariance, we
analyze the Polyakov loop in terms of the Dirac modes in SU(3) quenched lattice
QCD in both confined and deconfined phases. First, to investigate the direct
correspondence between confinement and chiral symmetry breaking, we remove
low-lying Dirac-modes from the confined vacuum generated by lattice QCD. In
this system without low-lying Dirac modes, while the chiral condensate $\langle
\bar{q} q\rangle$ is extremely reduced, we find that the Polyakov loop is
almost zero and $Z_3$-center symmetry is unbroken, which indicates quark
confinement. We also investigate the removal of ultraviolet (UV) Dirac-modes,
and find that the Polyakov loop is almost zero. Second, we deal with the
deconfined phase above $T_c$, and find that the behaviors of the Polyakov loop
and $Z_3$-symmetry are not changed without low-lying or UV Dirac-modes.
Finally, we develop a new method to remove low-lying Dirac modes from the
Polyakov loop for a larger lattice of $12^3 \times 4$ at finite temperature,
and find almost the same results. These results suggest that each eigenmode has
the information of confinement, i.e., the "seed" of confinement is distributed
in a wider region of the Dirac eigenmodes unlike chiral symmetry breaking, and
there is no direct correspondence between confinement and chiral symmetry
breaking through Dirac-eigenmodes.
