  The restriction of space-time dimensions to "2+1" leads us to a novel quantum
field theory which has the Chern-Simons term in its action. This term changes
the nature of gauge interaction by giving a so-called topological mass to a
gauge field without breaking the gauge symmetry. We investigate how a dynamical
mass of fermion is affected by the topological mass in the non-perturbative
Schwinger-Dyson method.
