  Possibility of spontaneous magnetization in QCD and magnetic properties of
quark matter is discussed by evaluating the magnetic susceptibility within
Fermi-liquid theory. The screening effects for gluons are taken into account to
figure out the specific properties of the magnetic transition in gauge
theories. It is shown that the static screening effect in terms of the Debye
mass does not necessarily work against the magnetic instability; it promotes
the instability, depending on the coupling constant and the number of flavors.
