  We investigate the role of Hund's coupling in the spin-wave excitations of
the ($\pi, 0$) ordered magnetic state within a five-orbital tight-binding model
for iron pnictides. To differentiate between the roles of intraorbital Coulomb
interaction and Hund's coupling, we focus on the self-consistently obtained
mean-field SDW state with a fixed magnetic moment obtained by using different
sets of interaction parameters. We find that the Hund's coupling is crucial for
the description of various experimentally observed characteristics of the
spin-wave excitations including the anisotropy, energy-dependent behavior, and
spin-wave spectral weight distribution.
