  The Kondo lattice model with Hund's ferromagnetic spin coupling is
investigated as a microscopic model of the perovskite-type $3d$ manganese oxide
(R,A)MnO$_3$ where $R$ and $A$ are rare earth element and alkaline earth
element, respectively. We take the classical spin limit $S=\infty$ for the
simplicity of the calculation, since the quantum exchange process seems to be
irrelevant in the high temperature paramagnetic phase. Magnetic and transport
properties of the system are calculated. In the hole doped systems,
ferromagnetic instabilities are observed as the temperature is lowered. The
giant magnetoresistance of this model is in excellent agreement with the
experimental data of (La,Sr)MnO$_3$.
