  We estimate coupling constants for effective Lagrangians of $D$-meson,
charmed, and light baryons from charmed baryon decay processes. First, we
calculate decay widths for the processes $\Lambda_{c} \to DN$, $\Sigma_{c} \to
D \Delta$, $\Sigma_{c} \to D^{*} \Delta$, and $\Lambda_{c} \to D^{*}N$ in
effective Lagrangian method and quark model picture with $^{3}P_{0}$ model. By
employing the coupling constants for $D^{*} \Lambda_{c} N$ interaction from
several literatures, the strength parameter $\lambda$ for $^{3}P_{0}$ quark
model is fixed in the decay process $\Lambda_{c} \to D^{*}N$. Then, the
coupling constants for the effective Lagrangians of $D\Lambda_{c}N$,
$D\Sigma_{c}\Delta$, and $D^{*}\Sigma_{c}\Delta$ interactions are estimated in
the decay channels $\Lambda_{c} \to DN$, $\Sigma_{c} \to D \Delta$, and
$\Sigma_{c} \to D^{*} \Delta$, respectively. These coupling constants will be
useful for further studies of charm hadrons.
