  An enhancement of antiprotons produced in p+d reaction in comparison with
ones in p+p elementary reaction is investigated.
  In the neighborhood of subthreshold energy the enhancement is caused by the
difference of available energies for antiproton production. The cross section
in p+d reaction, on the other hand, becomes just twice of the one in elementary
p+p reaction at the incident energy far from the threshold energy when
non-nucleonic components in deuteron target are not considered.
