  The pseudoscalar meson-baryon octet interaction is studied within a nonlinear
realized Lagrangian, and then the Bethe-Salpeter equation is solved in the
unitary coupled-channel approximation. In sector of strangeness $S=-1$ and
isospin $I=0$, only one pole is generated dynamically in the 1400MeV region,
which might correspond to the $\Lambda(1405)$ particle. When the case of
strangeness zero is studied, the $s-$ and $u-$ potentials are taken into
account in the kernel, and a resonance state is produced in the 1500MeV region,
which might be a counterpart of the N(1535) particle.
