  The semileptonic decays of $\Lambda_{b}\to\Lambda_{c}^{(*)}\ell\nu_\ell$ and
$\Lambda_{c}\to\Lambda^{(*)}\ell\nu_\ell$ are studied in the light-front quark
model in this work. Instead of the quark-diquark approximation, we use the
three-body wave functions obtained by baryon spectroscopy. The ground states
$(1/2^{+})$, the $\lambda$-mode orbital excited states $(1/2^{-})$, and the
first radial excited states $(1/2^{+})$ of $\Lambda_{(c)}^{(*)}$ are
considered. The discussions are given for the form factors, partial widths,
branching fractions, leptonic forward-backward asymmetries, hadron
polarizations, lepton polarizations, and the lepton flavor universalities. Our
results are useful for the inputs of heavy baryon decays and understanding the
baryon structures, and helpful for experimental measurements.
