  A lot of branching ratios of the exclusive $c \to d/s\ell\nu_\ell$
($\ell=e,\mu$) decays have been quite accurately measured by CLEO-c, BELLE,
BABAR, BES(I,II,III), ALEPH and MARKIII collaborations. We probe the R-parity
violating supersymmetric effects in the exclusive $c \to d/s\ell\nu_\ell$
decays. From the latest experimental measurements, we obtain new upper limits
on the relevant R-parity violating coupling parameters within the decays, and
many upper limits are obtained for the first time. Using the constrained new
parameter spaces, we predict the R-parity violating effects on the observables,
which have not been measured or have not been well measured yet. We find that
the R-parity violating effects due to slepton exchange could be large on the
branching ratios of $D_{d/s}\to e\nu_e$ decays and the normalized
forward-backward asymmetries of $D_{u/d}\to \pi/K \ell\nu_\ell$ as well as
$D_s\to K \ell\nu_\ell$ decays, and all branching ratios of the relevant
semileptonic $D$ decays are sensitive to squark exchange couplings. Our results
in this work could be used to probe new physics effects in the leptonic decays
as well as the semileptonic decays, and will correlate with searches for direct
supersymmetric signals at LHC and BESIII.
