  We study the effect of the Gauss-Bonnet term on vacuum decay process in the
Coleman-De Luccia formalism. The Gauss-Bonnet term has an exponential coupling
with the real scalar field, which appears in the low energy effective action of
string theories. We calculate numerically the instanton solution, which
describes the process of vacuum decay, and obtain the critical size of bubble.
We find that the Gauss-Bonnet term has a nontrivial effect on the false vacuum
decay, depending on the Gauss-Bonnet coefficient.
