  The analysis of the spin wave excitations in two-dimensional isotropic
Heisenberg ferromagnet is performed with a single skyrmion in the ground state.
We employ the ideas of semiclassical quantization method, duly modified for the
use of the lattice model and Maleyev-Dyson boson representation of spin
operators. The resulting Schr\"odinger equation for magnons describes the
dispersion and wave functions of spin-wave excitations with strictly
non-negative spectrum. In contrast to usual ferromagnet, we demonstrate the
existence of three zero modes, corresponding to conformal symmetries
spontaneously violated by the skyrmion configuration.
