  We report chemical abundances of 14 young $\alpha$-rich stars including
neutron-capture elements based on high-quality optical spectra from HIRES/Keck
I and differential line-by-line analysis. From the comparison of the abundance
patterns of young $\alpha$-rich stars to those of nearby bright red giants with
a similar metallicity range ($-0.7<[\mathrm{Fe/H}]<-0.2$), we confirm their
high $\alpha$-element abundances reported by previous studies based on
near-infrared spectroscopy. We reveal for the first time low abundances of
$s$-process elements and high abundances of $r$-process elements. All the
abundances are consistent with those seen in typical $\alpha$-rich population
of the Galactic disk, and no abundance anomalies are found except for
Li-enhancement in one object previously reported and mild enhancement of Na in
two stars. In particular, the lack of $s$-process enhancement excludes the
hypothesis that mass transfer from asymptotic giant branch stars plays an
important role in the formation of young $\alpha$-rich stars. The high
frequency of radial velocity variation (more than $50\%$) is also confirmed. We
argue that mass transfer from low-mass red giants is the likely dominant
formation mechanism for young $\alpha$-rich stars.
