PURPOSE: To enable an engine driving to be carried but without increasing a capacity of a commercial power supply by a method wherein an AC of the commercial power supply is changed into a DC and charged in a battery cell, when a voltage of the commercial power supply is more than a predetermined voltage, the commercial power supply is connected to an engine driving type heat pump device and in turn when the voltage is less than the predetermined value, a battery cell is connected.

CONSTITUTION: An electrical charging means 103 in a power supply device 101 for an engine driving type heat pump device changes an AC of a commercial power supply 100 into a DC and charges in a battery cell 102. A DC/AC converting means 105 changes a DC of the battery cell 102 into an AC. In turn, the power supply device 101 detects a voltage of the commercial power supply 100 through a voltage sensing means 104. In the case that a voltage in the commercial power supply 100 is more than a predetermined value, the commercial power supply 100 is connected to an engine driving type heat pump device 1 through a changing-over means 106 and when the value is less than a predetermined value, the battery cell 102 is connected to the heat pump device 1. With such an arrangement as above, it is possible to prevent the engine driving type heat pump device from being rapidly stopped due to a voltage drop or a power failure and the like.