  A new rapid energization process within a supernova shock transition region
(STR) is reported by utilizing numerical simulation. Although the scale of a
STR as a main dissipation region is only several hundreds of thousands km,
several interesting structures are found relating to generation of a root of
the energetic particles. The nonlinear evolution of plasma instabilities lead
to a dynamical change in the ion phase space distribution which associates with
change of the field properties. As a result, different types of large-amplitude
field structures appear. One is the leading wave packet and another is a series
of magnetic solitary humps. Each field structure has a microscopic scale (~ the
ion inertia length). Through the multiple nonlinear scattering between these
large-amplitude field structures, electrons are accelerated directly. Within a
STR, quick thermalization realizes energy equipartition between the ion and
electron, hot electrons play an important role in keeping these large-amplitude
field structures on the ion-acoustic mode. The hot electron shows
non-Maxwellian distribution and could be the seed of further non-thermal
population. The "shock system", where fresh incoming and reflected ions are
supplied constantly, play an essential role in our result. With a perpendicular
shock geometry, the maximum energy of the electron is estimated by equating a
width of the STR to a length of the Larmor radius of the energetic electron.
Under some realistic condition of M_A = 170 and \omega_{pe}/\Omega_{ce} = 120,
maximum energy is estimated to ~ 10 MeV at an instant only within the STR.
