A power generation system includes a compression unit which compresses a gas, a storage which stores the compressed gas output from the compression unit, a first expansion unit which generates first power and outputs a first exhaust gas, a heating unit which heats at least the stored gas output from the storage, a second expansion unit which generates second power and outputs a second exhaust gas, a first regenerator which performs a first heat exchange between the second exhaust gas and the stored gas output from the storage, to generate a first heat exchange gas used to generate the first power and a first regenerator gas, and a second regenerator which performs a second heat exchange between the first exhaust gas and the first regenerator gas to generate a second heat exchange gas used to generate the second power after heated at the heating unit.