  We develop the theory of momentum map for the Maxwell-Lorentz equations with
spinning extended charged particle. This theory is indispensable for the study
of long-time behaviour and radiation of the solitons of this system. The
development relies on the Hamilton-Poisson structure of the system. As an
example, we apply the theory to the rotation group of symmetry, calculating the
expression for the conserved angular momentum. We check the coincidence of this
expression with known classical invariant.
