  We analyze the instanton transitions in the framework of the gauge invariant
variational calculation in the pure Yang-Mills theory. Instantons are
identified with the saddle points in the integration over the gauge group which
projects the Gaussian wave functional onto the gauge invariant physical Hilbert
space. We show that the dynamical mass present in the best variational state
provides an infrared cutoff for the instanton sizes. The instantons of the size
$\rho<1/M$ are suppressed and the large size instanton problem arising in the
standard WKB calculation is completely avoided in the present variational
framework.
