  We discuss the reheating temperature in the instant preheating scenario. In
this scenario, at the last stage of inflation, the inflaton field first decays
into another scalar field with an enormous number density via the instant
preheating mechanism. Subsequently, the produced scalar field decays into
normal matter accompanied by the usual reheating mechanism. As an inflationary
model, we identify the inflaton as a field which gives rise to a mass for the
right-handed (s)neutrino. One of the interesting consequences of the instant
preheating mechanism is the fact that the reheating temperature is proportional
to the mass of the decayed particle, {\it the right-handed sneutrino}, $T_R
\propto M_R$. This is very different from the ordinary perturbative reheating
scenario in which the reheating temperature is proportional to the mass of the
inflaton.
