In a parallel running control apparatus for an inverter generator A having a first, second and third inverters each connected to three windings wound around an alternator driven by an engine and converts alternating current outputted therefrom to direct/alternating current to output alternating current, and first, second and third controllers to control turning ON/OFF of the switching elements, and the inverter generator A is configured to run in parallel with at least one inverter generator B which is configured to be same as the inverter generator A to output a three-phase alternating current.