NOVELTY - A fuel cell power generating device comprises fuel cell module which is equipped with fuel cell stack and fuel modifier, fuel gas supply part which supplies fuel gas to fuel cell stack, oxidizing agent gas supply part which supplies oxidizing agent gas to fuel cell stack, water vapor supply part which introduces water vapor into feed route of fuel gas, water carburetor which generates water vapor, temperature measurement part, and control part which controls electric power generation based on acquired temperature of water vapor measured in temperature measurement part and/or waste gas.    USE - Fuel cell power generating device used as solid oxide fuel cell electric power generating apparatus, polymer electrolyte fuel cell electric power generating apparatus, phosphoric acid fuel cell electric power generating apparatus and molten carbonate fuel cell electric power generating apparatus.    ADVANTAGE - The malfunction of water supply is reliably detected. The electric power generation of fuel cell power generating device is safely controlled.    DETAILED DESCRIPTION - A fuel cell power generating device comprises fuel cell module which is equipped with fuel cell stack for generating electric power by reaction with modified fuel gas and oxidizing agent gas and fuel modifier for modifying hydrocarbon type fuel gas, fuel gas supply part which supplies fuel gas to fuel cell stack through fuel modifier, oxidizing agent gas supply part which supplies oxidizing agent gas to fuel cell stack, water vapor supply part arranged at boundary part of fuel cell module which introduces water vapor obtained by vaporizing water supplied using heat of waste gas discharged from fuel cell module into feed route of fuel gas, water carburetor which generates water vapor, temperature measurement part which is equipped in discharge port vicinity of water vapor of water carburetor and/or discharge port vicinity of waste gas, and control part which controls electric power generation based on acquired temperature of water vapor measured in temperature measurement part and/or waste gas. INDEPENDENT CLAIMS are included for:    (1) control program; and    (2) control method of fuel cell power generating device.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of the control method of fuel cell power generating device. (Drawing includes non-English language text).    Controlling step of air supply system (S102)    Controlling step of fuel gas supply system and water vapor supply system (S103)    Monitoring step of temperature of fuel cell stack (S104)    Comparing step of temperature of fuel cell stack and predetermined temperature (S105)    Starting step of electric power generation (S106)