  The change with time of the system consisting of the quantum object and the
macroscopic measuring instrument is described on the base of the uniform
dynamic law, which is suitable both evolution and reduction processes
description. It is the integral wave equation with kernel in the form of a path
integral. It is shown, that wave function collapse is the specific
transformation which is fundamentally differ from Shr\"odinger's evolution.
Specifically, a formal cause of the collapse is a local time derivative
(infinite large) of the potential energy. Such transformation can not be
described using mathematical apparatus of conventional quantum mechanics.
