  We investigate the effect of adiabatic regularization on both the tensor- and
scalar-perturbation power spectra in \textit{nonminimally} coupled chaotic
inflation. Similar to that of the \textit{minimally} coupled general
single-field inflation, we find that the subtraction term is suppressed by an
exponentially decaying factor involving the number of $ e $-folds. By following
the subtraction term long enough beyond horizon crossing, the regularized power
spectrum tends to the "bare" power spectrum. This study justifies the use of
the unregularized ("bare") power spectrum in standard calculations.
