  We performed an ultrasonic measurement for the heavy-fermion compound
CeRhIn$_5$ to investigate the origin of the field-induced anisotropic phase in
high magnetic fields. The transverse elastic constant $C_\mathrm{T} = (C_{11} -
C_{12})/2$ and the ultrasonic attenuation coefficient $\alpha_\mathrm{T}$ show
clear anomaly at $B^\star = 28.5$ T, which was discussed as the electronic
nematic transition point. In addition, $C_\mathrm{T}$ exhibits acoustic de
Haas-van Alphen oscillation below 28.5 T. These elastic anomalies around
$B^\star$ indicate an electric quadrupole ordering of $O_{x^2-y^2}$ accompanied
by $B_\mathrm{1g}$ crystal symmetry breaking and Fermi surface reconstruction
due to the quadrupole-strain coupling, which results from itinerant $4f$
electrons and the $p$-$f$ hybridized state.
