  We consider domain walls in the $Z_3$ symmetric NMSSM. The spontaneous $Z_3$
discrete symmetry breaking produces domain walls, and the stable domain walls
are problematic. Thus, we assume the $Z_3$ symmetry is slightly but explicitly
broken and the domain walls decay. Such a decay causes a large late-time
entropy production. We study its cosmological implications on unwanted relics
such as moduli, gravitino, LSP and axion.
