Abstract: 
A novel effect on the decay of a false vacuum in view of quantum field theory is discussed, which is induced by a field coupling to the scalar field related to a firstorder phase transition. This effect of the environment can never be included in the traditional method using the effective potential, and, in fact, acts as dissipative and fluctuation effects on tunneling phenomena. We show that the tunneling probability of the false vacuum may be drastically altered. It is also clarified what kind of interaction enhance or suppress the probability.
