  We report the measurements of the $^{29}$Si Knight shift $^{29}K$ on the
noncentrosymmetric heavy-fermion compound CePt$_{3}$Si in which
antiferromagnetism (AFM) with $T_{\rm N}=2.2$ K coexists with superconductivity
(SC) with $T_{c}=0.75$ K. Its spin part $^{29}K_{\rm s}$, which is deduced to
be $K_{\rm s}^{c}\ge 0.11$ and 0.16% at respective magnetic fields $H=2.0061$
and 0.8671 T, does not decrease across the superconducting transition
temperature $T_{c}$ for the field along the c-axis. The temperature dependence
of nuclear spin-lattice relaxation of $^{195}$Pt below $T_{c}$ has been
accounted for by a Cooper pairing model with a two-component order parameter
composed of spin-singlet and spin-triplet pairing components.
  From this result, it is shown that the Knight-shift data are consistent with
the occurrence of the two-component order parameter for CePt$_{3}$Si.
