  A new mechanism of black hole formation in a first order phase transition is
proposed. In vacuum bubble collisions the interaction of bubble walls leads to
the formation of nontrivial vacuum configuration. The consequent collapse of
this vacuum configuration induces the black hole formation with high
probability. The primordial black holes that have been created by this way at
the end of first order inflation could give essential contribution into the
total density of the early Universe. The possibilities to establish some
nontrivial restrictions on the inflation models with first order phase
transition are discussed.
