A method of driving a heating unit for a fuel cell reformer, a reformer applied with the method for driving the heating unit, and/or a fuel cell system including the reformer. The method includes: supplying an oxidant to the heating unit and absorbing the oxidant by a fuel oxidizing catalyst of the heating unit; supplying a fuel at an excessive amount to the heating unit and absorbing the fuel by the fuel oxidizing catalyst of the heating unit; and supplying the fuel and the oxidant to the heating unit at a stoichiometric ratio of the fuel to the oxidant ranging from 1:1 to 2:1, wherein the heating unit generates heat through an oxidizing catalyst reaction between the fuel and the oxidant.