  We review the characteristics of nucleosynthesis in 'Hypernovae', i.e.,
supernovae with very large explosion energies ($ \gsim 10^{52} $ ergs). The
hypernova yields compared to those of ordinary core-collapse supernovae show
the following characteristics: 1) Complete Si-burning takes place in more
extended region, so that the mass ratio between the complete and incomplete Si
burning regions is generally larger in hypernovae than normal supernovae. As a
result, higher energy explosions tend to produce larger [(Zn, Co)/Fe], smaller
[(Mn, Cr)/Fe], and larger [Fe/O], which could explain the trend observed in
very metal-poor stars. 2) Si-burning takes place in lower density regions, so
that the effects of $\alpha$-rich freezeout is enhanced. Thus $^{44}$Ca,
$^{48}$Ti, and $^{64}$Zn are produced more abundantly than in normal
supernovae. The large [(Ti, Zn)/Fe] ratios observed in very metal-poor stars
strongly suggest a significant contribution of hypernovae. 3) Oxygen burning
also takes place in more extended regions for the larger explosion energy. Then
a larger amount of Si, S, Ar, and Ca ("Si") are synthesized, which makes the
"Si"/O ratio larger. The abundance pattern of the starburst galaxy M82 may be
attributed to hypernova explosions. Asphericity in the explosions strengthens
the nucleosynthesis properties of hypernovae except for "Si"/O. We thus suggest
that hypernovae make important contribution to the early Galactic (and cosmic)
chemical evolution.
