  Using the Kondo lattice model with classical spins in infinite dimension,
conductivity in the perovskite-type $3d$ transition-metal oxide (La,Sr)MnO$_3$
is theoretically studied. Green's functions as well as spontaneous
magnetization are obtained exactly on the Bethe lattice as a function of
temperature. Conductivity is calculated from the Kubo formula. Below the Curie
temperature, resistivity as a function of magnetization is in a good agreement
with the experimental data. Anomalous behaviour in the temperature dependence
of the optical conductivity observed in (La,Sr)MnO$_3$ is also explained.
