  To understand anomalous transport properties of EuB$_6$, we have studied the
spin-polaron Hamiltonian incorporating the electron-phonon interaction.
Assuming a strong exchange interaction between the carriers and the localized
spins, the electrical conductivity is calculated. The temperature and magnetic
field dependence of the resistivity of EuB$_6$ are well explained. At low
temperature, magnons dominate the conduction process, whereas the lattice
contribution becomes significant at very high temperature due to the scattering
with the phonons. Large negative magnetoresistance near the ferromagnetic
transition is also reproduced as observed in EuB$_6$.
