The problem of stability of a self-gravitating, infinite homogeneous gas in the presence of magnetic field is investigated. The medium is assumed electrically and thermally conducting. The effect of porosity, electrical conductivity, thermal conductivity and Hall current is investigated on the self-gravitating plasma flowing through porous medium. The relevant linearized equations of the problem are stated and dispersion relation is obtained. The effect of Hall current on the condition of the instability of the system is examined for both longitudinal and transverse mode of propagation and found that in longitudinal propagation Hall effect does not change the condition of instability but modifies the Alfven wave mode. The stability of the system is discussed by applying Routh-Hurwitz criterion and it is found that Jeans criterion determines the stability of the system. Thermal conductivity and porosity have a destabilizing influence on the medium. The general condition for instability of the system is also derived.