NOVELTY - The fuel cell electric power generation system (S) has reformer (3) which produces reformed-gas (R) which has hydrogen as a main component. The fuel cell (6) is operated using as fuel reformed-gas supplied from reformer. The desulfurizing-apparatus (D) has a heating unit (21) to heat desulfurizing agent (1a) such as silver zeolite adsorption agent in a container (C) to 50-200 degrees C, while the raw fuel gas (P) is accommodated inside the container.    USE - Fuel cell electric power generation system.    ADVANTAGE - The agent can be heated according to the necessity so that the desulfurization performance can be improved and frequency replacement of the agent can be reduced.    DETAILED DESCRIPTION - A dew point sensor (Se1) detects moisture level contained in raw fuel gas which flows into container. A heating control unit (32) controls the operation of heating unit according to moisture level detected by the detection unit. The heating control unit stops heating process when the detected moisture level is less than the preset reference level. The heating control unit starts heating process when detected moisture level is more than preset reference level. The heating unit exhausts heat discharged from the fuel cell, while desulfurizing agent is heated. The thermal storage mechanism (22) thermally stores the recovered exhaust heat. The heat supply structure supplies the heat thermally stored in the thermal storage mechanism. The heating control unit controls heating unit to heat desulfurizing agent for a fixed time, before fuel cell starts electric power generation. A temperature detection unit (Se2) detects the temperature of the desulfurizing agent. The control unit (38) starts electric power generation process based on detected temperature, after the desulfurizing agent is heated. A desulfurizing-apparatus removes sulfur compound from the raw fuel gas supplied to fuel cell. The desulfurizing agent adsorbs a sulfur compound in the raw fuel gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of the fuel cell electric power generation system. (Drawing includes non-English language text)    Desulfurizing agent (1a)    Reformer (3)    Fuel cell (6)    Heating unit (21)    Thermal storage mechanism (22)    Heating control unit (32)    Control unit (38)    Container (C)    Desulfurizing-apparatus (D)    Raw fuel gas (P)    Reformed-gas (R)    Fuel cell electric power generation system (S)    Dew point sensor (Se1)    Temperature detection unit (Se2)