  Based on the new valley equation, we propose the most plausible method for
constructing instanton-like configurations in the theory where the presence of
a mass scale prevents the existence of the classical solution with a finite
radius. We call the resulting instanton-like configuration as valley instanton.
The detail comparison between the valley instanton and the constrained
instanton in $\phi^4$ theory and the gauge-Higgs system are carried out. For
instanton-like configurations with large radii, there appear remarkable
differences between them. These differences are essential in calculating the
baryon number violating processes with multi bosons.
