  The sign problem is notorious in Monte
  Carlo simulations of lattice QCD with the finite density, lattice field
theory (LFT) with a $\theta$ term and quantum spin models. In this report, to
deal with the sign problem, we apply the maximum entropy method (MEM) to LFT
with the $\theta$ term and investigate to what extent the
  MEM is applicable to this issue. Based on this study, we also make a brief
comment about lattice QCD with the finite density in terms of the
  MEM.
