  THz time-domain spectroscopy was used to directly probe the low-energy
(0.5--5 meV) electrodynamics of the charge-ordered manganite
Pr$_{0.7}$Ca$_{0.3}$MnO$_3$. We revealed the existence of a finite peak
structure around 2--3 meV well below the charge gap $\sim300$ meV. In analogy
to the low-energy optical properties of the well-studied low-dimensional
materials, we attributed this observed structure to the collective excitation
mode arising from the charge-density-wave condensate. This finding provides the
importance role of the quasi-one dimensional nature of the charge and orbital
ordering in Pr$_{0.7}$Ca$_{0.3}$MnO$_3$.
