To obtain a method and an apparatus for composite power generating, which have: an excellent adaptability to the change of an electric energy, required for a small-scale power generation such as a distributed power generation; an excellent power generation efficiency; and also an excellent reliability of the apparatus.

The method of generating the power uses: a first generator using at least one of a steam turbine and a gas turbine as a drive source; a converging detonation generator for generating a conductive fluid by ionizing or dissociating a combustion exhaust gas by generating the detonation by an intermittent combustion; and a second generator for generating the conductive fluid generated by the converting detonation generator as an operating fluid. The method of generating the power includes a step of providing a power required steadily by the first generator, and a step of providing a fluctuation part of a power demand by the second generator.