  We show that a hybrid inflation model with multiple waterfall fields can
result in the formation of primordial black hole (PBH) with an astrophysical
size, by using an advanced algorithm to follow the stochastic dynamics of the
waterfall fields. This is in contrast to the case with a single waterfall
field, where the wavelength of density perturbations is usually too short to
form PBHs of the astrophysical scale (or otherwise PBH are overproduced and the
model is ruled out) unless the inflaton potential is tuned. In particular, we
demonstrate that PBHs with masses of order $10^{20}\, {\rm g}$ can form after
hybrid inflation consistently with other cosmological observations if the
number of waterfall fields is about 5 for the case of instantaneous reheating.
Observable gravitational waves are produced from the second-order effect of
large curvature perturbations as well as from the dynamics of texture or global
defects that form after the waterfall phase transition.
