  We report $^{115}$In nuclear-quadrupole-resonance (NQR) measurements of the
pressure($P$)-induced superconductor CeRhIn$_5$ in the antiferromagnetic (AF)
and superconducting (SC) states. In the AF region, the internal field $H_{int}$
at the In site is substantially reduced from $H_{int}=1.75$ kOe at P=0 to 0.39
kOe at $P=1.23$ GPa, while the N\'eel temperature slightly changes with
increasing $P$. This suggests that either the size in the ordered moment
$M_{Q}(P)$ or the angle $\theta (P)$ between the direction of $M_{Q}(P)$ and
the tetragonal $c$ axis is extrapolated to zero at $P^*=1.6 \pm 0.1$ GPa at
which a bulk SC transition is no longer emergent. In the SC state at $P=2.1$
GPa, the nuclear spin-lattice relaxation rate $^{115}(1/T_1)$ has revealed a
$T^3$ dependence without the coherence peak just below $T_c$, giving evidence
for the unconventional superconductivity. The dimensionality of the magnetic
flutuations in the normal state are also discussed.
