To provide a high humidity combustible gas power generation system capable of preventing reduction of amount of power generation and possible to be provided even in the case wherein an external heat source can not be obtained.

The high humidity combustible gas power generation system is structured of a gas compressor for compressing high humidity combustible gas, a cooling device for cooling the high humidity combustible gas supplied from the gas compressor, a heating device for heating the high humidity combustible gas supplied from the cooling device, a power generating device using the high humidity combustible gas, which is supplied from the heating device, as fuel, a casing for housing the gas compressor, the cooling device, the heating device and the power generating device, and a cooling fan for blowing cooling air to cool inside the casing. With this structure that the heating device is provided most downstream of the cooling air blown by the cooling fan, the high humidity combustible gas power generation system capable of preventing reduction of amount of power generation and possible to be provided in the case wherein an external heat source can not be obtained can be provided.