  We argue that a primordial black hole is a natural and unique candidate for
all dark matter. We show that, in a smooth-hybrid new double inflation model, a
right amount of the primordial black holes, with a sharply-defined mass, can be
produced at the end of the smooth-hybrid regime, through preheating. We first
consider masses < 10^(-7)M_sun which are allowed by all the previous
constraints. We next discuss much heavier mass 10^5 M_sun hinted at by entropy,
and galactic size evolution, arguments. Effects on the running of the scalar
spectral index are computed.
