  The meson-baryon molecular components for the $N^{\ast}$ and $\Delta ^{\ast}$
resonances are investigated in terms of the compositeness, which is defined as
the norm of the two-body wave function from the meson-baryon scattering
amplitudes. The scattering amplitudes are constructed in a $\pi N$-$\eta
N$-$\sigma N$-$\rho N$-$\pi \Delta$ coupled-channels problem in a meson
exchange model together with several bare $N^{\ast}$ and $\Delta ^{\ast}$
states, and parameters are fitted so as to reproduce the on-shell $\pi N$
partial wave amplitudes up to the center-of-mass energy 1.9 GeV with the
orbital angular momentum $L \le 2$. As a result, the Roper resonance $N (1440)$
is found to be dominated by the $\pi N$ and $\sigma N$ molecular components
while the bare-state contribution is small. The squared wave functions in
coordinate space imply that both in the $\pi N$ and $\sigma N$ channels the
separation between the meson and baryon is about more than 1 fm for the $N
(1440)$ resonance. On the other hand, dominant meson-baryon molecular
components are not observed in any other $N^{\ast}$ and $\Delta ^{\ast}$
resonances in the present model, although they have some fractions of the
meson-baryon clouds.
