A power generation system according to the present invention includes: a fuel cell system (101) including a fuel cell (11) and a case (12); a ventilation fan (13); a controller (102); a combustion device (103); and a discharge passage (70) formed to cause the case (12) and an exhaust port (103A) of the combustion device (103) to communicate with each other and configured to discharge an exhaust gas from the fuel cell system (101) and an exhaust gas from the combustion device (103) to the atmosphere through an opening of the discharge passage (70), the opening being open to the atmosphere, and the ventilation fan (13) is configured to discharge a gas in the case (12) to the discharge passage (70) to ventilate the inside of the case (12), and the controller (102) causes the ventilation fan (13) to generate predetermined pressure or higher when the fuel cell system (101) is in a power generation stop state and the combustion device (103) is operating.
