PURPOSE: To prevent instantaneous large current from flowing to a starter to a power unit in starting in the starter power unit for starting an engine so provided so to compress refrigerant in a gas heat pump air conditioner system.

CONSTITUTION: Three-phase a.c. current of 200V as commercial power is decreased, for example, to 12V by a power source transformer 3 and converted into d.c. current by a rectifying circuit 5. A large capacity capacitor 41 is changed by this large current. A controller 37 monitors the charged state of the large capacity capacitor 41 and allows ON of a starting switch 11 when the charged electricity becomes the specified voltage. When the starting switch 11 is turned on, a contact 45 is closed, and current discharged from the large capacity capacitor 41 is allowed to flow to a starter motor 9, so as to start an engine. The current to flow to the power source transformer 3 and the rectifying circuit 5 may have the magnitude for changing the large capacity capacitor 41, large current is not required.