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.