To provide a power generation system that can efficiently generate power from high temperature heat of combustion while suppressing an increase in the size of a device as a whole.

The power generation system comprises a mixed gas generator 11 for generating mixed gas, a gas turbine 12 that uses the mixed gas as fuel, and a generator 14 coupled to the gas turbine 12 via a rotary shaft 13. The mixed gas generator 11 generates mixed gas by electrolyzing water to generate a hydrogen gas and an oxygen gas in a mole ratio of 2:1 and mixing them evenly. The mixed gas has an extremely a high combustion temperature of 2,000 to 2,500°C and, when used as fuel, develops thermal expansion and a sudden increase in volume under a high temperature condition, so that a small quantity thereof can produce high pressure to efficiently rotate the gas turbine 12.